Flat head screwdriver it open, and then run a knife round the sealer. Clean the mating faces, wire brush drill bit, emery paper, whatever. Make sure theyre 100% dry. Make sure the sump surface is straight and true. Apply good sealer. Not too much or you'll end up with it blocking the oil pickup. And the 10mm bolts only go to something like 8Nm so dont go mental. And tighten them up the same kinda way youd do a cylinder head.