Yes you can. Nubus DOS cards are pretty slow though. If you want anything faster than (I think) a 486, you're looking at a PCI card, which rules out your Rocket.Hrm, can you use a Radius Rocket in a NuBus PowerPC? Combine that with a NuBus DOS compatibility card, and wish granted!
OrangeMicro made the only true Nubus slot x86 cards as far as I know. The one in the 6100DOS was an '040 PDS card with a 601 PDS adapter bracket.
/edit/ seems there was also the following:
There ya go. No G3 and no HPV/AV video as the PDS slot is taken, but add a good Nubus video card and the Rocket, and you're in business. Presumably it'll fit the 8100 PDS as well.