I just went through the process of removing and cleaning a problem IAC valve, and then having to do it again three days later (!!) when the car developed a persistently high idle causing me to buy a new IAC valve.
The trick to removing w/o tearing off the intake manifold is to jack up the care fairly high so that you can reach up to where that little bugger sits crammed in nicely among other parts. there is just enogh room to get an 8mm ratcheting box wrench on the two little bolts holding the IAC on.
But the harder trick is fumbling with your new IAC to orient it so you can get these tiny bolts back in their holes. Just take a deep breath--you can do this. Its possible somebody with tiny hands could reach down to pin it in place while you search for the bolt holes. i did the replacement at 10:00 last night without a helper.
DEFINITELY take off your neg. battery cable and let the car sit for a while before you start it up.