I agree, it's a swine of a job.
Gearbox off.
Sump off.
Flywheel off.
Rear bearing cap and bottom half of oil seal housing are one and the same
Remove old oil seal.
Remove the cruciform oil seals from the bearing cap.
Clean everything in sight, twice.
Put the new seal in place, I don't think you can use gasket sealant.
Apply sealant to the bearing cap, fit new criciform seals and apply more sealant, refit cap.
Tighten the bearing cap, at which point the oil seal flips out.
Swear. Go inside for a cup of tea, this is taking longer than you though
In the classic words "reasembly is a reversal of the removal procedure".
Then watch it leak just as badly, if not worse, becasue it's a poor peice of design.