I would like to make my own mod for Soldier of Fortune Linux version by Loki. Apparently, Loki, before going under, ported the SDK for SoF. The only two things I found that resembled any sort of SDK was on the CD. They was called gtkpak and pakx, but I'm not too sure if that is it. Looking around the directory, it seems like it maybe it, but I cannot compile for it requires something called egcs, which I have yet to install because gentoo sources do not carry it. Gotta fix that soon. Is this what I am looking for? The Windows SDK seems to included several programs, even a 3D modeler (the sofgradient). Does anyone have any knowledge in this? Thanks in advance.

I know nothing of the SDK, but egcs is (was?) an experimental optimized version of GCC. Here's a page:
http://gcc.gnu.org/egcs-1.1/

hasn't been updated since 1999? So I suppose it is abandoned. Maybe the old version will still work for you. Maybe everything good in egcs was rolled into mainline gcc?

Indeed it was. In fact, since 1999 gcc IS egcs.