k, so here's my ghetto fix. And before you follow any of my instructions I just want to state for the record that I am most definitely not a mechanic or anything of the sort. I guessed my way through this process. Not to mention i'm not the best instructor, just giving fair warning. Also this is for this particular license plate with turn signals that I purchased.
http://www.meancycles.com/Home.asp?PartID=213962&AccCategoryID=2345&AccCategoryTypeID=0&BikeModelID=0&ManufacturerID=0&BikeType=Cruiser&CompanyID=0
Disconnection:
1. I took off the housing for the rear lights, the bracket for the rear light electrical and the shitty plastic extension for the license plate.
2. I disconnected the rear turn signals from the black housing (put these away because you won't be needing them unless you want four turn signals).
Fabrication:
3. buy 2 straight metal 4" brackets from home depot.
4. Buy 2 6mm x 16 mm alan screws, thread should be 1 mm apart (these will replace the two screws that bolt the silver plastic housing to the black metal brackets. These are slightly longer than the stock ones because you will be inserting the two metal brackets between the housing and brackets.)
5. (figure 1) Mark off the width of the metal bracket at the bottom of the silver housing. Do this same step for the other side.
6.(figure 2) Take a dremel with a cut off wheel and cut the silver housing where you had marked off the width of the bracket. Do this same step for the other side.
7. (figure 3) Temporarily sandwich the new bracket between the silver housing and the black stock bracket. Take the license plate and butt it to the bottom of the silver housing and give it about 1 or 2 mm for a slight cushion. Then mark off where the screw hole of the license aligns with the new bracket. Do this same step for the other side.
8. (figure 4) Drill a hole the size of the screw that will be going into the back of the lisence plate frame. Do the same step for the other bracket.
9. (figure 5) This is how it should look at this point if you temporarily put it together.
Installation:
10. Take the license frame and insert your license plate into the frame. Attach the brackets to the top two screws of the license frame. I used red locktite to make sure the screws don't vibrate out, you can probably use the blue locktite but I kept loosing those fasteners on my plate so i'm a lil more paranoid about it and didn't want to take a chance.
11. (figure 6) Wire up the lights and the relay. I decided to put the relay and most of the wiring right behind the plate just because I'm a lazy bastard and didn't want to deal with making it nice and hiding it behind the fender. But you should place the wires how you feel is best.
a. I cut of the connectors from the stock turn signals as well as the brake light that sits on just ontop of the stock plate that is attached to the black extension piece. This way I could re-use them on the new lights and it would connect directly back to how it was originally (highlighted in yellow). Make sure you write down which color connecter is associated to what. The middle yellow is for the brake light and the grey and black connecters are for the turn signals.
b. Attach the relay to the new wires as directed. by the instructions on that came with the relay.
11. Now just put everything back on your bike.
12. Before you completely attach everything back together permanently, first just connect the wiring together and test that turn signal connectors match. Light the bike up and test the turn signals. (I did this and had the right turn signal blinking left and vice versa. luckily those stock connecters are interchangeable and I have my black to grey and grey to black. oh well, no one will see that anyway.)
13. Put the stuff back on to the bike:
a. Attach the black bracket back on to the fender and make sure you use red locktite on the screws.
b. slide the wires from the bike into the rubber housing on the black bracket. yellow goes in the middle.
c. connect the wires from the plate to the wires that should be on the black bracket. (I hope you remembered the color set up).
d. (figure 7) sandwich the new brackets from the license frame in between the bolts on the black bracket and the silver bracket and use the new screws you bought to compensate for the added width from the new brackets. Again make sure you use red locktite on these screws as well.
video of new plate