This is probably common knowledge to all the Omega cognoscienti, but it was new to me. During the strip down of my 3.2 spares car it became clear that I should have removed the drivers seat before taking the battery and all the engine wiring out, because in order to access the seat mounting bolts the powered drivers seat has to be slid all the way back to access the front ones and all the way forward to get to the rears. On the passenger seat it was possible to hotwire the motor, but for some reason on the drivers seat, perhaps because it has a memory module, this didn't work...
Fortunately there is a failsafe screw in the end of the motor, which you can turn with a suitable flat bladed screwdriver.
I'm sure if you had a suitable adaptor an electric drill would speed this up no end, because it requires a huge number of turns to move the seat even a small distance. Anyway sometime later we had revealed the rear bolts holding the seat frame down and it could be removed.