UV Mapping a Disc

[KeenKernel]

I'm rather new to XSI Mod Tool, and I've been having some trouble with a polygon mesh disc. It seems that with a Disc that when I go to apply the texture and set the texture projection , it won't let me set it to UV. I know that with a surface everything works right, but I can't use that anyhow. Any workarounds or alternatives would be greatly appreciated.
Thanks!