Hey guys,
Just checked out the wiring for this door beep on my R33 Series 2. The black with purple stripe wire is correct with the first post, however I did it a different way that required no cutting.
On the ignition barrel, there are a couple of wires going into a clip that directly plugs to the barrel and there are 2 wires that appear hard wired to the barrel but about 5 - 10cm down there is a clip for them (a bit like a fly lead). The first plug is for the lights so don't touch that one. The one on the side that has the sorta flylead is the one you want to unclip (for the r33 s2 it was a black flat plug).
All headlights, power windows and mirrors still work.