So I want a on/off button to control my Methanol kit. I was thinking about getting another heated rear screen button with the green LED and modifying it to control the Methanol kit. Does this sound realistic?

The on/off switch that comes with the kit looks like this:

Description: "The switch is a single pole 1 way SPST. It can be used to activate any kit, allowing the progressive controller to take over once on."

How hard do you think this would be?

I bought a spare rear windscreen switch a while back with the intention of using it as an on/off switch for something, my plan was to remove the switch plate and replace it with one of the blanks, from what I remember I was told i'd need to use a relay in the circuit to make it work, still not got round to do anything about it. Theres norm a few 2nd hand switches going on ebay for a couple of quid, I was £1.50 for mine iirc

I think it'll be a piece of cake.

If you're confident with electronics & can take dashboards apart of course

With the money you have i would take it to an auto electrician for a pukka job! Moneys nowt to you money bags

I imagine that itll need a positive and negative to the switch from the meth kit loom, then an illumination feed off the headlight switch so it lights up when the lights are on. Youll then need to wire it up so the led lights when the meth kit is activated.

If you can get a switch with the connector and a small amout of loom it would be much easier to make the connections aswell.