I'm an actually, honet-to-gosh, paid the $20 years ago, registered user and GS supports BOTH the demo and final versions.
It's just that Q3TA uses a command string like:
"E:\Quake III Arena\quake3.exe" +set fs_cdpath "e:\Quake III Arena\baseq3" +set fs_game missionpack
Ooops...figured it out.

It's the same as Q3. Find the folder and the command string is "quake3.exe". [smacks forehead]
D'oh!
Thanks for trying to help anyways.
