To replace the main bearings, you have to split the case. You can not do this in the car. The rod bearings (I believe what you are referring to when you say throwout) would be almost impossible too.
Ok ... thanks for that info. I've never torn into a Subaru motor before, but I can see it's a flat 4, horizontally opposed motor, somewhat like an old, air-cooled VW. I rebuilt a VW motor a long time ago, but I guess I just assumed the Subaru would be different.
Well ... If I need to split the case, I might as well get the machine work done and do the job properly. :-|