So on with it!
Since I don't have a radio in my car anymore this was a really simple change, if you're still using your radio (AM/FM) you will need to pick up a cheap cable. The cable can be found here - Ebay Link
It's an antenna splitter - 1 female incoming, 2 male outgoing.

Essentially this involves:
- removing the dash bezel/fascia (http://www.elantragtclub.com/id243.html)
- (re)moving the hvac controls out of the way
- removing the stereo to access the antenna plug
- unplugging the antenna plug
- attaching the splitter
- plugging one end back to the radio
- finding the ETACS
- unplugging the white end antenna wire
- plugging the other end of the splitter (you may need an extension, depending on the length of splitter you get)
- Next up, walk a long way away from the car and see how well your remote works
Then you get to put the stuff back together (radio, hvac, fascia)