It wasnt really that hard
Take the tank off, dont do what i did though, which was to put 16L of fuel in it last week, it weighed a bloody ton!! and my petcock valve doesnt have on "off" position so i was also getting covered in petrol for a while.
Take off the side panels and airbox. Then you can get to the top nut from above ( 14mm and 11mm spanners)
The bottom nut is a slightly different story as it has had 15 years worth of crud thrown at it. I resorted to using a grinder to shear the bolt off and then hammered it through.
Then simply pull the old unit out and pop your new one in. You might need a mate to hold the rear wheel at this point, so you can line up the bottom pin. I didnt bother with the swingarm bearings as it was getting dark, but while you are there im sure it is worth looking into.
A pretty straightforward job, if youve got the tools and a bit of patience.