Hi Bob
I haven't done it myself...
But there should be a trigger wire on your new style controller.
You button would be supplying 12V to that wire on the controller.Someone once mentioned putting a diode in the original wire so you don't back-feed the sensors.
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews