I went exploring, looking for the way to back up your files in Soilhouette Studio. The files are encrytped but you can do a back-up so that you will not loose them. While doing that, I found the "Patterns" folder and went exploring and experimenting....and found a way to import and use your own pattern.
This is probably just useful if you have a pattern that you use all the time. It involves overwriting one of the the original patterns so some people will be a little hesitant to try it. But I made a back-up first and figured I couldn't make any irreparable mistakes!
Find the Silhouette program files on your computer. Every OS one is a little different, but here is where mine are on my Vista:
OK, but on to patterns. See the patterns folder - with the "?" mark? The patterns in the subfolders are actually the ones you see in the Silhouette Studio program! Doesn't this look familiar?
But then I though, maybe it needs the original name. So I renamed my pattern to same as one of their files, and copied it in. Voila! I have my own fill. Now it still shows up as in the menu choice as their pattern (the red-orange argyle) but when I select it, it fills with my pattern!
Here is my pattern, notice how it is renamed as red-orange argyle.png:
Oh, and by the way, you can already use your own patterns in Make-the-Cut!. They are called "textures" but it is a very easy to process to add your own in MTC. In MTC it is important that they are less than 256x256 pixels in size, otherwise they slow down Windows. IMHO MTC is actually superior to SS in both ease of use as well as options. Both programs trace image files but with MTC you can also use SVGs, something that SS cannot do at this time.