Funky has done this and I'm sure there is a guide in the how-to section.
HID on the pre-facelift cars isn't an automatic failure, but technically speaking any HID upgrade without having headlight washers or auto-levelling headlights breaks VOSA regulations and is not road legal.
That being said my FN2 has neither and passed the MOT at a main dealer with the HIDs in.
Pre facelift cars just require HID kits with bulbs designed for reflector lenses as these will not cause glare to other road users.