You'll need a large "C" clamp for compressing the caliper piston. I dont recomend loosing the cap and allowing the pressure to blow back into the system.
It will push the old fluid(with contaminates and moisture that has settled to the lower line) backwards through the system and can cause several problems with your ABS system down the road.
Open the bleeder valve on the caliper to releave the pressure.
Other then that you will also need some brake grease for the caliper slide pins,
and any other odds and ends that would typicaly need checked and replaced as needed.