dunno if that above linked method works on the 03 or not, but most any other year doing so with throw a SVS warning light. Someone with an 03 try it and let us know.
The only other way I know of is to get your hands on one of the DRL Kill kits that were made by a few guys on gagt.com a few years back. It killed the DRL's, killed the auto headlight feature and allowed you to use your fog lights independant of any other lights, ie fogs on only, fogs with hi beams, etc. I got one, but I ain't parting with it anytime soon. :P