Well that is a way of doing it.
I am not over keen on messing around with the loom.
I have myself achieved the same by soldering a diode from the high beam relay to the low beam relay (cathode side of the diode on the low beam + coil side of the relay and Anode side on the + coil side of the High Beam relay).
The benfit of this is that it is reversible in minutes and also means you don't have to mess around with the loom. (I have got some pictures somewhere and will try and post them up).
Oh and I have also since fitted a HID kit, if you fit a HID kit this mod is essential as the HID light unit takes time to fire up and this could be potentially dangerous as when the high beam is switched off it will take a few seconds for the low beam to come to full brightness.
Pete :thumbup