should be pretty easy, i put a p75 (1.2 8v mpi) in a carb'd car. I basically left the cars wiring alone, used the fuel cut off switch wire as the switched live for the engine harness. I think the only other bit of wiring it needed was the fuel pump - i mounted an inline pump where the coil pack normally sits. To get it running i just earthed it to the body - never did finish that part properly but plan was to fit an inertia switch somewhere inside, cinq or sei one probably fit nice up behind the dash and run the earth through that to the body so if you crash the fuel will stop pumping.
I did strip down my engine harness and remove unnecessary wires but you needn't go that far.