Here ya go, Toasty.

The center diff lock detection switch is used for both the center diff lock light and as an input for the rear diff lock computer. To allow rear lock operation independent of the center diff, splice a wire with a connection to ground and an enabling switch to the yellow/blue wire to the sensor switch on the center diff/tcase. When the enabling switch is on, rear diff lock operation should be enabled. Source: 92-95 fsm wiring diagram for rear diff lock circuit.

I don't think the switch shown above will work without the computer. It's a momentary switch that sends an enabling signal to the rdl computer, and the computer latches the circuit to the pump on and the release valve off until another signal, the off pulse from the shown switch, unlatches the circuit in the rdl computer and the release valve in the pump is enabled to let the air our of the rdl.

The only way to run the locker without the computer is a simple on/off spst switch, and use a 10a fuse which is what the oem system uses.