Yes, the cranshaft can be removed from below, but I would encourage otherwise. If you're about to delve into that much work, one might consider the condition of the remainder of the engine and act accordingly. Why are you interested in replacing the main and rod bearings? How many km's on the engine? Are you burning oil? poor oil pressure? Compression/leakdown test results?

I guess what I'm trying to get at is, why not remove the engine (not that difficult), have a lot more to play, and do more than just the bearings (rings, hone, headgasket, block gaskets/seals, head freshen etc. ???).

I was very hesistant upon my first engine removal, but found it to be quite straight forward. Just take lots O' photos

Dave M