I may not have this right since I wired mine about 4 years ago but I am pretty sure when you ground the circuit you will have current in the ground leg. I have a Kirban 5 switch panel in the ashtray. I ran a common ground through all of the switches to a bolt on the firewall and then just took the fan ground and converter ground and ran them to the middle leg of the switch, switch lites and the switches perform their function. You have voltage available in the line, It needs to be grounded to complete the circuit. I know I have no relays, and there are only two wires going to each switch. The light in the switch is in series to ground.
My line lock is wired differently since it breaks the 12+ signal to my momentary switch on the shifter. A single ground is connected (this only grounds the light) and the 12+ goes into the 1st leg of the switch, when on the switch lights and then I have power to the momentary switch, hit the momentary and the additional LED light I added at the console gauge cluster goes on. This light is seperately grounded and fed directly from the 12+ to the line lock, if the light is lit the line lock is on. Lighted switch in the ashtray only indicated power to the line lock is available.
Clear as mud. If you follow the instructions on GNTTYPE you should be in pretty good shape.
Bob