Never done an LDV van but a few suggestions :
1. Put a length of plastic tube over the bleed nipple and undo it a turn or two so when the piston DOES move fluid will come out the pipe and not back to the reservoir.
2. On some calipers the pistons screw back in, they don't just push. If that's the case there should be some way of turning the piston without gripping the outside of the piston (which will damage it).
3. If it is just a push job then you will need a G cramp and a block of wood, or a big fat screwdriver and several bits of wood so you can lever it back in - keep the piston lined up straight.
Good luck
Richard
January 2009