The ideal solution here would be a cloth simulator --- if you end up rendering in POV-Ray, this may be of use:
http://jeberger.free.fr/cloth/cloth.html. Not sure if there's any way to get the geometry back into AC3D from here, if needed.
Unfortunately, I've had terrible luck finding a free standalone cloth simulator --- just about every simulator I've run across has been designed as a plugin for another 3D package, usually a higher end one like Maya, Studio, etc.
Wish I had more advice to offer here --- I personally haven't gotten to a project that involved cloth, so haven't heavily researched it yet, but, hopefully, the above link will lead you to something useful.
Dennis