here's the H-D part numbers for the contacts that will go on the wires and fit into the stock connectors - 73191-96
Instructions for the removal and insertion of the contacts from the plastic housings are in the service manual (you do have a service manual?)... even if you don't have a crimper, you can carefully "crimp" the contacts on with a pair of needle-nose pliers and then solder them. MAKE SURE YOU SOLDER THEM!!
You can re-use the factory connector housings, but if you want to get new ones, here's the part numbers for the plastic connector housings (you will still need the contacts from above)
73152-96WE - Left rear signal
73152-96BK - right rear signal
73153-96BK - license plate light
73191-96 - contact pins/terminals
(you will need at least 6 of them for what you are doing... get a few extras, trust me
If anyone wants the terminals put onto their lights, you could send them to me and for $15.00 (shipping and parts), I'll put them on for you... however, most dealers, if you have a good relationship with them, would probably get someone to crimp them on for you if you buy them.
BTW, the wires from the signals only need to be about a foot long.