My advice: go to another mechanic.
Or:
drain oil completely
undo both front and rear engine mounts
drop cross member
undo front engine mount support from the block
undo all bolts holding the sump on
using a sump seal cutter or a flat blade, slice sealing gasket to remove pan
clean sump mating surface (remove all traces of liquid gasket), while your there clean out the sump too
remove all traces of gasket from mating surface on engine block, be careful not to leave any small fragments near the main bearings
For cleaning the 2 surfaces, i'd use a rag soaked in thinners, it will clean off the crap well that might be left and completely evaporates after it's dried, leaving zero residue
put new gasket/liquid gasket on pan
reinstall
also to note, the 2 (i think) bolts holding the sump on the gbox side, the one closest to the front of the car is a complete [i seem to suffer from tourettes] to get to both to tighten and loosen. I'll try and scan the relevant info later.