jonas my old school apex'i is for sale at $40 if you want it. 5 wires.

1 to ignition
1 to constant +12volt
2 to accessory (the 2 can both splice into the same ACC wire)
1 to ebrake (optional: if you hook this up, you have to have the ebrake up when you shut the car off for it to kick in...if you dont hook it up you can risk leaving the car in gear or neutral (with no ebrake to keep it in place) when its timing down/off.)

i'll even help you wire it. its way easy.

ps - enjuku sells harnesses for like $15 for s13 that owrk with like hks/apex'i and greddy i think. mine has no harness clip though just wires.