LED latch switch fitted to dash in the spare hole left of steering wheel
Power from the fuse box on drivers side
Valves are controlled purely from the dash, on or off. I suppose on the GT all you would need to do is wire the vacuum solenoid independently to a switch and therefore make it independent of the sport button. You could run the power cable from the vaccuum solenoid along the break lines into the engine bay and back into the drivers fuse box via a wring hole that is already there. A t amp in line fuse off the cigarette lighter circuit should suffice.
Took me about 4 hours all in all including 3mm vaccuum lines, connectors, solenoid, latch switch and wiring.
Hope that helps