I've read that a WRT54G could act as a bridge or access point with the right firmware and configuration. I'd like to bridge my WRT54G to my WRT54GP2. What'd be the least painful avenue to take?

I've also seen that some 3rd party firmwares offer this option (i.e. Alchemy, Freeman, HyperWRT) & I'd like to know which one would be the safest to use. Also, if the firmware doesn't work then how can I reset the router back to its original firmware (i.e. factory default). Thank you.