The option connector plug for the MK3 is available.
I don't know the exact pinouts but a multimeter will reveal all. The common pins are:
Permanent power
Ign pos 1
Ign pos 2
Reverse selected
Door open
Lights on
If there is enough demand I can ask the supplier, with forum permission, to create a thread here. He currently supplies connector plugs for:
Civic 8G, 9G, 10G, CRV, Jazz MK3
I'm still looking for a closeup of the MK4 fusebox.