You simply can’t. It is not possible. Even if it were possible…the performance wouldn’t be any better than the AGP slot.
Part of what makes Smoke on Linux so quick is the Quadro 4000 board (or 4500). There’s lots of graphics accelerated operations.
Putting an AGP Quadro into a PCI-E slot would be like taking a stock Mitsubishi Lancer and putting an Evo body kit and badges all over it. The engine is still the same tiny little engine from the stock lancer. (Not sure how many car people are here that’ll get that 😆 )