Have the button installed already:

Here are the instructions (not a really good start):

Here is the wiring diagram for the FTO ignition circuit:

Now, Black goes straight to earth, thats a no brainer
Red is the "Power Path that passes through the ignition" which im guessing means the current from the fusable link ie the red wire that goes into the back of the ignition barrel
The first blue wire (labelled green in instructions) is the "Terminal 15 - ign" which im guessing is perhaps ignition system which would make it Black-White
The 2nd blue wire is the "Terminal 50 - The Power Path From Ign to Starter Motor" which im guessing is perhaps Black Red
Any help would be appreciated