I'm planning on doing the same thing you are. I'm went to
www.trdsparks.com and looked at the installation instructions they had listed for the oem LED lights. I think I'm going to tap into the same wire they use for those lights and run a wire from that to back behind that panel located at the bottom center of the dash. There I'm going to create a junction point. I'm just going to put eyelets on all of the wires and hold them together with a nut and bolt. Then I'll wrap it with electrical tape. I'll just attach a sheet metal screw to the body for a ground if I can't find a bolt already in place that will work. Doing it this way means that the lights I'm adding will be wired to the headlight switch. If I start to blow fuses I'll wire in a relay. I was thinking of maybe wiring in the lights to turn on when the doors open but then I'd want them to turn on with the headlights as well. I could do this using a relay, just haven't decided yet.
I found a better deal on neon lights off of ebay than I found in the stores.
As far as cutting the end off of the lights go for it just make sure before you do that you know which wire is + and which is -. If you can't tell by looking at the wires pull the plug apart the wire going to the center is +.
