OK, so to answer two questions with one fell stroke:
I did sketch my mini-wardrobe line drawings by hand, scan them into a file and then alter them in Photoshop. Normally, I would just use the online line drawings from the pattern company. But in this case I was trying to put everything together while watching "Life On Mars" (yes Angie A., John Simm does love me) and I didn't want to drag out the laptop just to do my planning. So instead, I sketched the garments I wanted to work with onto one sheet (this was handy for layout purposes anyway) and then I scanned the whole thing in later when I was ready to mess with color.
So in thinking about that, I decided I would waste a bunch of blogging energy by writing a tutorial. Yay, tutorial! My thoughts are that this will be totally old hat for some of you, totally boring for others and maybe helpful for a handful. Yay, handful! There are lots of online and magazine resources for a billion different ways to do wardrobe storyboards, so if you're interested you might do a search and see what you can see. However, here's my two cents. My really really long-winded two cents (yes Angie A., I'm talking to you again). This process looks way more complicated than it actually is, so if you haven't ever tried it, give it a chance. It's fun!
I would normally do this (and I did do this) with Adobe Photoshop. However, Photoshop isn't accessible to everyone. But Lo! There is a free-ware photo editing software from Microsoft called Paint.net. As far as I can tell, this is a like a scaled-down version of Photoshop. It's also freeware, which I can guarantee you Photoshop is not. And holy Hare Krishnas, have you seen Adobe's latest prices?? Oops. I probably shouldn’t say that. I work for an Adobe Service Provider and I'm the Adobe Girl.
Awesome. Now I'm imagining being made out of wet clay.
So anyway, I'm going to do this tutorial with Paint.net which should be interesting since I've never used it before... this should at least tell us if it is actually "like Photoshop but easier".
If you're not interested, now would be the time to bail.
HOW TO MAKE A COMPUTER GENERATED WARDROBE STORYBOARD USING PAINT.NET (for absolute rank beginners)
Don't panic if it looks difficult, it's not. Just follow the steps closely. It takes way longer to read this all than it actually does to do the work.
STEP ONE - Getting your line drawing:
Find a line drawing of your garment. You can either copy-and-save the image from an online source, scan from the pattern envelope or hand trace a hard copy. If you hand trace, you have to have the ability to scan in your drawing to create an image file (for instance, a nice happy .JPEG). I found this line drawing at the Burda Fashion website and right-mouse clicked to save the image.

Next I opened up Paint.net and used the "open" menu command to open the drawing (by going to File>Open...). The file you're creating is called a "drawing" (not to be confused with the "drawing" of your garment).
In your workspace you will find several palettes (these are the boxes with tools or pieces of information relating to your drawing).
STEP TWO - Making Your Cut-Out, Part 1
Basically we want to make a cut-out of your garment so you can add color to only the inside of the line drawing and not the background.
Go to the Toolbar palette, which is the long skinny palette on the left with lots of icons in it. These are what you use to select, move, color and do lots of other things. For our purposes, we want to select the white background of the line drawing. "Selecting" means that only whatever is highlighted blue can be altered (for instance only that area will be painted or copied). Click on the fourth tool in the left-hand column, which is called the "magic wand" tool (if you hold the mouse over the tools without clicking a pop-up will show you what the tool is called). The magic wand tool selects based on similarity of pixel color. In other words, it tries to find everything adjacent to the place where you click that is relatively similar to what you clicked on.

Using the magic wand tool, click on the white background of the line drawing. This should select everything that's white on the background of the line drawing. If you've selected something you didn't want, you can go to Edit>Deselect (or Control+D key command) and unselect everything.

To add to your selection, you can also use a keyboard command. So for instance in this example there's a white space above the neckline that didn't get selected when I clicked the first time. To add this area, hold down the Control key. Notice how the magic wand pointer changes to include a little plus sign. That means you can click again and add to your current selection.
(Side note: if you're new to this whole process, this system works best with a high-contrast line drawing like the sample. If your image has a lot of gradient detail or lots of gray area, using this tool is more complicated. I would still use it but I'd have to mess with it a bit. High-contrast black-and-white line drawings should select well because you mostly only have white or black.
Also note, if your line drawing has gaps in the black lines, the tool will bleed through that gap and select part of the image inside the garment. You can close up these gaps by using the drawing tool with black selected. If you're scanning your own drawings, be sure to keep this in mind and close up any gaps before you scan it.)
When you're satisfied with what you've selected we can move on to the second step of making the cut-out. Be sure your selection stays selected throughout the next steps. If you accidentally lose your selection, go back and reselect or go to Edit>Undo until your selection shows up again.
STEP THREE - Making Your Cut-Out, Part 2
Now we need to get the area inside the dress selected and not the area outside the dress. Go to Edit>Invert Selection. This causes everything you don’t have selected to be selected and vice versa. Now the shape of the dress and everything inside is selected. You now have a cut-out of your garment.
STEP FOUR -Making Layers:
At the bottom right corner is a palette called "Layers". Think of layers as pieces of transparent acetate. You can color or draw on each new layer, stack it up on top of other layers (in whatever order you like) and make complex images. Just like your teacher used to do in 6th grade with the overhead projector, only better.
When you opened your image, that became the "background" layer. Next you need to create a New Layer by clicking on the "Add New Layer" button at the bottom right corner of the Layout palette. See? A brand spanking new layer with nothing in it called "Layer 2". You can change the name of the layer if you want to but it's not necessary.
Those grey and white checkers mean it's transparent. This second (and any additional) layer is where you'll be adding your color to test out what fabrics you want to use.
STEP FIVE - The Really Fun Part (a.k.a. Adding Color)
To begin with, don't get overly concerned with what color you use. Just pick any color. You can change this later.
Be sure you still have Layer 2 active in the Layers palette. You want to do this next step in the empty layer and not on your line drawing layer.
Go to the Tool palette and select the Paintbucket tool (this looks like, amazingly enough, a little bucket of paint). At the bottom left you should have a color wheel. Click anywhere in this to select the color you want. When you have your color chosen, click in the middle of the dress shape with the Paintbucket pointer to fill the whole selected area with a solid color. You should end up with a block of color that is dress-shaped.
STEP SIX - Show The Drawing Lines:
In this last step, you want to make the line drawing under the color block show up again. Make sure you continue to have Layer 2 selected in the Layer palette. Now go to the menu bar and select Layers>Layer Properties... and in the dialog box under "Blending Mode" selected "Multiply".

To describe it easily, this setting causes the layer to visually merge with the layer below it. You're "multiplying" the pixels of both layers. You should be able to see your line drawing and the color you chose.
Now you can fill the Layer 2 cut-out with any color you want. Use the Paintbucket tool, choose your color and be sure to click inside the previous color in order to fill that shape. If you click outside the previous color, you'll fill the background.
If you want to try multiple variations, use "Edit> Save As..." to save a new file for each change and you'll have a new image for each color.
And there you have it, the fast-and-dirty way to make some storyboard images.
No really. That's fast and dirty. Seriously.
You can do it!
Now go forth and create some storyboards for us to admire.
(disclaimer: I take absolutely no responsibility for the accuracy or coherence of this tutorial. Use at your own risk. If your computer blows up or your brain melts, that is completely and utterly your own fault. Really. On the other hand, if this works out amazingly well for you, I am brilliant and you must send me presents.)