You'll need a 7mm hex wrench or socket to remove the calliper bolts (two each side) and when I did mine it a fair amount of grunt to shift the little beggars. I didnt need to use a wind back tool I just manually pushed the pistons back in (and I dont eat spinach for breakfast
The caliper bolts shouldn't be very tight as the have an unusual 9mm thread. Other than that, just make sure you have a piece of emery cloth, a file and or a scraper to remove the built off crud from the carriers to allow the pads to move freely in and out. Don't remove too much though, otherwise the pads will rattle in the carriers.
As Gary's site does not appear to work correctly, I'll explain the proceedure. Here is the proceedure for front brakes. Remember you can turn the steering for easier access.
After jacking up etc, remove the spring anti rattle clip from the caliper (best to use Vise or Mole grips). Position these near the anchor, and use a slight twisting motion to pull out.
Remove caliper retainer plastic end caps and slacken and withdraw both the 7mm hex bolts in the inside of the caliper.
Move caliper body out of the way (you may first have to disconnect the brake pad wear indicator wire).
Remove brake pads.
Unbolt the 12mm headed disc retaining bolts on the flange face.
Remove caliper carriers (17mm bolts) which can be fairly tight due to thread lock.
Clean flange face to ensure no brake vibration develops.
Clean new discs and fit retaining bolts.
Clean carrier and ensure pads are a sliding fit.
Push back, or even better, bleed fluid from caliper so piston is fully retracted. (Make sure fluid does not leak from reservoir and damage paintwork.) I use very large pipe pliers for this.
Apply anti squeal compound to brake pad backing sparingly where it contacts carrier and caliper.
Fit retaining spring.
Connect up pad wear indicator wire for idiot light (if desired).
Pump up brake pedal to ensure pedal travel is not excessive which suggests an issue with fit or air in hydraulic system if it was bled.
Do other side.