I've heard the Gromacs core takes advantage of the AltiVec in G4s for Folding. How do you get this core to start working with Folding? What do I need to do?
Yes, when you download the latest client, configure it, and start it, it will download the latest Gromacs core which is AltiVec-enabled. Even for G3s, the latest Gromacs core is far quicker than the earlier ones.