Hi, I always fit my own (even in a 335!), but I did a course with Stephen Delft on guitar repair in the 70's and do all the set up work on my guitars. I also like to do different wiring, just ask Tim ;) I am using the new 4 pole 5-way switch which BKP sells to get series wiring on my h/s/s and strat sets. This gives you some of the Brian May sounds that are almost impossible to get with standard wiring.
My only problem so far is fitting the Crawler and Nailbomb as they are overwound a bit and require the pickguard opening up a bit.
I use a 40 watt iron, keep the tip clean and use a desoldering pump when taking off the old wires.
Cheers
Phil