I must tell you that I an Not an auto electrician but I can get by.
So if anyone is intrested in doing this mod heres a wiring diagram of what I have done.
It will probably work on other models but you may have to find another trigger wire 86 to activate the relay. The trigger wire can only be live when engine is running and not when the ignition is turned on.
I did this by wiring the relay in first then I used a length of wire from 86 on the relay wrapped around a sharp prong which I could push into the connector at back of dash while engine was running once the headlight came on I then tried it with just the ignition. If the headlight comes on with the ignition then its no good so try again.