Hi,
Much the same as this......
Engine Start kit for Mini R50 R52 R53 R55 R56 R57 Cooper S Works One D 1.6 | eBay
Don't see this being hard to fit at all , i take it you will need to locate your ignition wires and some sort of power source , maybe from the cigarette lighter as this would have enough amps required , your kit also must come with a relay for it to work.
I had a look at these but i thought since you still have to insert the key anyway i decided against it.
If you are confident in wiring then this will be a simple task.