I'll leave the logistics questions to others who may have been to TJ more recently but a driver's license alone is not proof of citizenship.

From the US State Dept. "tips for travelers to Mexico" website at:

http://travel.state.gov/travel/tips/...onal_1174.html

"Bring either a U.S. passport or a certified copy of your birth certificate and current, valid photo identification."

This applies to native-born U.S. citizens; naturalized citizens should replace "birth certificate" with "naturalization certificate".

You didn't specify your nationality and the rules will very probably be very different if you're a citizen of a third country.