I wired one into my Plus 4 before going touring. If you look in the spare wheel well inside at the top, the wiring for the stop tail runs there. My cyclops light had a connector located there in the original loom. I bought the correct connector (male+female) from ebay and plugged a tee into the loom as a take off for the light. Then used a phono jack at the top of the spare wheel hole, just inside to easily plug in the stop light for on top of the luggage.

This was the connector i used : http://www.ebay.co.uk/itm/2-Way-Econosea...=item3f411ea348

Hope this helps