It does work for the 2003 HCH (works for 2003-2005).
Using it doesn't specifically cause IMA lights, but if you use it flog your battery, one will probably appear even sooner, or if you use it to protect your battery, it could prevent an IMA light. Like Peter said, whether or not it prevents the IMA/check engine light depends on the nature of your failure.
On that note, I set a new personal best for my commute:
My previous best was 71.1 going the other direction on the same route. The route has 26 stoplights in 10.5 miles, but 3 of them are set to flashing yellow until 8:00am.
Sam