This is one that I did on a blue screen. It's appeal is limited to my daughter but it shows what can be done in Vegas 6. Therefore, no critiques of the video please!
Make sure that your cloth has no creases and is matt. Even better, I would recommend a bright (gaudy) blue or green matt emulsion and paint a wall. Lighting should not be direct but can be bounced off an opposite white wall or wall/ceiling combination to diffuse the light and minimise shadows as much as possible. Stand your subject away from the wall to make any last vestiges of shadow even less pronounced.
Remember that the colour chosen for the wall shouldn't be close to anything worn by the subject shot. Even a blue shirt against a gaudy blue wall will prove difficult to separate in Vegas.
Finally, take time to play around with different combinations of brightness/contrast to make the background as distinct from the subject as possible.
my link can be found at;
http://www.youtube.com/watch?v=hgqYUdTd7FY
Hope this helps?