I would check that you cant slide them inbetween the bumper and radiator etc, I have a TF and the manual says that you have to remove the bumper to fit them, but after a bit of checking they slide inbetween the radiator and the bumper. Also you might be able to get them in from underneath with the car raised up (just a thought)
Hope one of these methods works! save taking that bumper off!
The black section of the bumper should come off and you can install them. But on the SW you have to take the bumper off as people started to steal them of the old 25/ZR as you just had to undo 3 screws on the from of the bumper where as the old 45/ZS had them on a mounting bracket on the back of the bumper. I can check at work tomorrow but you might have to take the bumper off to reach the wires anyway.
You do not need to remove the bumper.The covers unclip easily,start at top corner towards middle of car,gently push down and pull forward,then unclip lower corner and they spin round on pins,give them a gentle pull and they come free.
A very good guide is avaliable on www.themgzr.co.uk under How to questions and guides.