Someone on R2R made a nem remover: pvc tube and rubber bands.
Cut some notches in the PVC as anchor points, use the rubber bands to hold it to rock over the nem.
Annoy the nem so it shrinks up, slip the tube over it, anchor it to the rocks, and wait. The nem will move up into the tube to get to the light. Then you can take it out easier.
Think they also used a piece of rubbery mat to seal the tube to the rocks; so the nem can't sneak out any cracks.