In all likelyhood you can't, sorry. I've been tryin the same thing with my IBM T22 and everyone I talk to says "Sorry, not sure those exist." All laptop vid cards are integrated (makes sense, where would you fit an AGP port?) so there's no upgrading, as is the case with most laptop parts.
Me "I bought a TNT2 M64, the BIOS says its a Vanta"
IOMagic "Theyre the same card"
Me "Um, no"