Yes the sump comes off in situ, after lowering x member etc to clear.
I've just installed a cometic, heard a lot of good things about them, with loctite 5900 around the ends of the half moon seals.
Are you 100% sure it's the sump, the oil pressure switches leak and spray oil all over the side of the block(as they point upwards) and this runs down and finds it's way all around the sump esp that side.
My switch leaked from between the plastic inner part(with the terminal in the middle) and the metal outer case part.
tabetha