Sorry for Bumping old thread:

Did ever someone knows of existence of SDK's for?:
Matrox Impression? in attachment is some *.c and *.h files that shows how they access video card functons (taken from MGA_3D-SuperPack_Ver_4 cd)
Matrox Millennium?
Paradise Tasmania 3D?
PowerSGL2 (Neon 250, Kyro, Kyro II)?

Can you please share what you found for CGL and S3 MeTaL.