Ok i got a rover 200, but the keys are missing

But all the docs are there and it is all legit. I can stil turn the ing on becasue we ripped off the barrel to get it home and on the back of the barrel there is a black box and inside that is a white funny shaped little thing that i can fit a smalish screwdriver in to turn the ing on and even turn the engine over. But i really want to make this road legel.
My idea (not always the best)
Fit a toggle switch for switching the ign on
Another switch for the lights and all that
And a push button to start it.
Before you bring up the matter of locking it, It has an alarm with remote central locking
All the help i get is most appericted!!