the only real thing that sucks about driling into the headlamps is when you break through, you usually kill the chrome inside the headlamp.. since you can't really put tape over it, it rips it up and it looks retarded.. maybe the grommet would help cover it? im not a headlight strobe expert.. but thats the only real reason i wouldnt want to put it there..
as far as drilling it, i dont see why not.. maybe you should look for another cheapie headlight on
ebay ($20 maybe?) from a tundra and use it as a test project.. thats what i would do