probably not the way to do it Steve but when I done the stainless pistons on mine, took pads out and pumped pistons out a bit....... managed to then grip and twist the pistons out from that point.
Took whole caliper off and used a nut and bolt with washers and nylon washers to put through the 'banjo?' then tightened to seal, to stop the fluid leaking out
(hope that makes sense?)
wasn't sure I wanted to clamp any lines, so done it this way and it worked fine.....