Going on the assumption you have the engine out. If the cam bearing walked out, then the cam is obviously junk or in need of some work, and a good cam is probably just as cheap as a rework. That being said, if the engine is out, I'd just cut the bearing with a die grinder or torch, no risk there since the cam is already fragged. If engine is in, I don't see any way around pulling it, as you're going to have to thoroughly clean the block after doing any kind of cutting on that bearing and I see no way around that. I've got a set of cam bearings heading my way from summit today for one I'm going through as a matter of fact.