is it better to just tap it off one of the bulb wires or should i go for the relay or fuse?

i.e. - i want the relay to trigger when highbeams come on, but it should be a clean/elegant install.

If you're relaying your high-beams, don't cut anything--use a male plug on one side and tape off the other plug. That way you can go back to stock with no permanent damage.

For auxiliary lights that comes on with the high beam, you can just use a tap on the wire of the driver's side high beam.

Edit: Nevermind on the first part--I guess this is for your driving lights.

yeah after some experimentation, i discovered that the switched ground wire on the 2005 hibeam was the white/black wire (on the 9005 plug). I used this in my relay coil/switch circuit to activate the lights.