It can be done, you'll likely wish you had gotten a root canal instead though.
An engine stand allows for the block to be inverted for this step. I can't imagine how you would support the crank while removing the mains - and then the reverse to install with fresh bearings - not to mention with the patience to plasti-gauge the clearances while on your back . . . which is typically at least two installations/torque ups with tear downs to read tolerances. By the third install you would probably be quite skilled at doing this on your back . . .
regards,
stock49
