and at the risk of sounding brash,,, "piece of cake"
took me about 10 minutes per side without having to remove anything at all,, other than the old lenses and rounded screws obviously!
remove the number plate to save scratching the reflective finish,
you will need a fine drill bit on a cordless,,
lift the boot lid up to chest hieght (stops you getting back ache if nothing else) and drill 5 or 6 holes around the screw untill you have pearsed the lenses,
gently tap a fine flat blade electrical driver in through one of the wholes to the inner side of the screw as this part is hollow,,
put your hand over the cover and gently pry the lense, which will pop off easy peasy and drop into your hand,, this is what you will be left with below
as seen in the picture,, use a small electrical screw driver to remove the old weak bit of lense from around the screw,, both mine popped off by wigglening the driver in a circular motion!!!
then simply use some small pump grips,, as seen below,, or long nose pliers to release the screw
insert the new led and lense and screw the badboy down,, hey presto,,, job done!
and heres what you should be left with if you take your time
fair enough,, not as easy as just unscrewing the ****** thing,, but saves all the hassle of taking the unit apart and/or even buying a new one!
ps,, sorry for the poor quality pics,, had to use my phone !