1. Remove wheel ( assuming you know how )
2. Remove retaining clip/spring
3. remove caliper guide bolts ( these are protected by a rubber sheath, remove plastic cap and unscrew 7mm allen key required
4 slide outer pad from caliper
5 Pull other pad from caliper
6 Push back piston to allow new pads to be inserted ( I used 2 small clamps/spreaders in spreader mode find in B&Q in tool section )
7 fit pads and refit in reverse order.
I am in the process of doing this job myself but I'm having trouble getting hold of a 7 mm allen key hope you have better luck.
Quoggy, February 2009