I don't think its that hard. I would think once you have the UIM off its pretty easy to do. Getting the UIM off/on is pretty easy and doesn't take too long. I might be wrong though, as there may be more to replacing the IMRC. But, I seriously doubt it would be THAT hard.

1999 Mystique LS V6 Alpine CDA-9807, Rear deck sub, Opt. TB, K&N RU-3530/MAF adaptor, custom heatshield, FSVT 17's, SCT 4-program chip, Eibach's/ST200's, Hella Fogs...