I found the following information from the link below. Thought it would be really helpful and looks fairly simple (and reversible).
Disable Auto Head Light and Day Running Lights
Disabling the Day Running lights and the Auto Headlight on feature is quite an easy mod and can be reversed just as easy. This mod takes approx. 10 min. and all the tools needed are a socket set.
1. Lift the trim plate from around the radio and climate control panel. No tools are needed as it is held on by pressure clips. Set it aside.
2. Take out the four hex screws holding in the radio in. (Note) You don’t need to disconnect the battery for this operation BUT if you do, make sure you know the code for your radio if it is enabled. You will need it to ensure your radio operates after putting it back in.
3. Move the radio aside and look into the dash. In the upper right corner on the firewall you will see a small black box with two wire harnesses attached to it (about the size of a pack of camels).
4. Lift the box in an upward motion, it’s on a slide clip. Bring the box out of the dash, there is plenty of wire to manage easily. Disconnect the wire harness with the BLUE wire in it, just let it hang out of the way. THAT’S IT!
5. Re-install the wire box, radio and faceplate.
http://members.tripod.com/bpador/modinstruction.html