i don't get why you want an IR switch. Why do you need your neon lights on remote? A manual switch would do. It also would be easier. Just run the wires to your fuse box for power (use a fuse tap), then wire that to a concealed switch under your dash (you will need to drill a small hole). They sell a plastic pry bars in the stereo section at walmart if you can't access the panel for a switch position.
If your set on making a IR remote. And you don't know anything about electronics, then it's going to take a lot of time and effort. Because if you build it wrong you can't erase, you have to build it again. But the things you'll need. proof board, solder, soldering iron, IR led's/ sensor's,a 555 timer chip, capacitors, voltmeter, transistors, potentiometer, resistors, diodes, bread board,, helping hands. But it will be harder working with 12volts w/o a bread board with it's own power supply so it would be better if you just used a 9 volt.