No, You do not need to remove the crossover.
Take the wires off first or have a friend hold it up so the weight are not on the wires when you take the bolts off.
The "new" starter weights much less and you will have more room to install the wires after you put the mini in place.
Before you first crank the engine with it, check the gear mesh first.
You will need a 16mm for the main wire and an eight mm for the start wire.