If you have any old AC power adapters laying around that you are not using just cut the round plug end off (make sure it fits first) and use that to plug into the white control box. Then connect the 2 wire to you 12v source(porch light). I never throw out my old power adapters.I keep them in box for future use just in case.
That how I wired in my 12v multicolored Led light strip. I wired it into my porch light. I also replaced my porch light assy and my scare light at the same time. I installed motion sensor porch light with the Led bulb and scare light assy. I was able to hide the small white control box inside the porch light behind the lens. I then drill a small hole in the porch light assy and added a micro toggle switch ( from radio shack) to it so I can switch between the Led light strip or the porch light. Here's the RV motion sensor porch light
http://www.starlightsinc.com/shop/pc...11&idcategory= and scare light I installed
http://www.starlightsinc.com/shop/pc...2&idcategory=4 . It works great. I purchased it from Amazon. They had the best price.