Looking at the schematic for the '01, it appears that the low beam has two sets of wires, one from the headlight switch and one from the DRL module. It might be as simple as removing the fuse to the DRL module (if you're into that sort of workaround). A switch could be installed on the wire to the DRL module, so that the DRLs can be selected on or off.
From what I could find, DRLs were never required in the U.S. - they were permitted (beginning with the 1995 model year) by the NHTSA. The NHTSA did set limitations on the intensity of the lighting used, but not that they be required on a vehicle. In 2001, GM petitioned the NHTSA to have DRLs required, but was denied in 2009 ["... the agency remains neutral with respect to a policy regarding the inclusion of DRLs in vehicles ..."].