First remove plastic cover in the boot to right hand side to expose aerial motor, there is a single 10mm bolt at the bottom remove it and unplug electrical connector, then you need to remove the chrome nut on the outside holding the aerial from the top, arrowed in pic
http://img86.imageshack.us/img86/687/existingro9.jpg
the old aerial will now just come out and you are left with a hole in the rear quarter
Next you need to fit cover/holder in rear quarter, the pic shows where i cut it back too, I needed to do this to get the stubby up far enough for it to seal.
http://img352.imageshack.us/img352/9825/insertea9.jpg
i then fitted the bracket from burna to the holder
http://img246.imageshack.us/img246/7047/bracketfixzh7.jpg
then the stubby screwed in the top of holder
http://img86.imageshack.us/img86/9774/bracketscrewfe6.jpg
with all these bits fitted together i pushed the aerial up from inside up through the cover fitted in rear quarter, this had to be pushed up hard to get a nice tight fit
then the cover in the pic is slipped over the stubby and clips to cover in the rear quarter to finish it neatly
http://img120.imageshack.us/img120/2145/coverhx6.jpg
the bracket that burna supplied is then fixed to the same fixing to the car body where the original aerial was secured, point to note i had to extend my bracket as it did not reach which makes me wonder if I did it right but everything else seemed ok
any question please ask