I installed an EOC switch today. Here is how I did it, should work on any 89-94 as far as I know.
1. momentary switch normally open
2. relay use a good one like Bosch 5 pole 30Amp
3. inline fuse holder capable of 20 amps
4. 15 amp fuse for holder
5. 16 gauge wire use no smaller than this or will over heat
6. ring terminal for grounding momentary switch
7. nylon ties
8. wire loom
9. (2) 1/4" male spade connectors for 16 gauge wire
10. (4) 1/4" female spade connectors used to connect wires to relay
11. Solder and soldering gun a must for underhood wires. Don't want to break down because of bad connections, Do you?
Begin by disconnecting battery. Pull 15 amp injector fuse in under hood fuse panel. Cut 2 sections of wire roughly 6 feet in length. Solder a spade connector onto fuse holder, and one section of above wire to other side of holder, mark this wire with a piece of tape at end. Solder another spade onto second wire used as return from relay. Run these 2 wires into underdash to mount relay. You will need the momentary switch grounded on one side, this will be to trigger relay. The other side of switch goes to relay. Diagram below. Mount your switch wherever it is easy to get to, I used my shifter knob. Once you have all connections made plug the fused wire into fuse panel and the unfused wire in as well. Pic below. Reconnect battery. Install fuse, match the size it calls for 15 Amp on my car. Start car, verify it runs. Press button verify it dies out.
To use while coasting shift to neutral for coast, hit button. Enjoy. Bump start vehicle, no key needed. Just release button, ease out in clutch in a higher gear, do not pop clutch, but do not overly slip either. Takes practice but saves alot of fuel. Questions just ask.
Edit: 85 and 86 are reversed on my diagram. These pins are the control side and reversible. One ground, One power. Makes no difference on the position of these 2.