I did this also and it worked great!
However, to make neater/more permanent connections, I went to Autozone to buy one of the Bussman ATC "Add-a-circuits" suggested by bobcivic. The guy at Autozone asked what I was doing and I explained everything and he immediately said, NO - you do NOT ever want to connect the hot AND the ground wires to the fuse box. He said it's a fire hazard. He said instead connect the ground wire to metal somewhere outside of the fuse box, which I did. So I only used one of the Bussman add-a circuits for the taillight fuse.
And here's why that won't work....when I turn the headlights on, the buzzer stays on even after I start the car.
So my question is, is this really a fire hazard like the Autozone guy said? Because apparently it won't work unless I use the rear defroster fuse and the taillight fuse.