Put a 12" section of plastic tunnel from a hamster habitrail in the tank, wait until he discovers it and then just pick it and him up and transfer them both to a pail. Its quick, easy and stress free. Put your hand over the end with his head in it.
Fishpoors's way is good. that's how we moved our work one and the incident passed completelly hastle free. First sign of a disturbance and our pleco ran into the tube without any coaxing.
thanks for the advice. we took him back so he could go into a larger home than a 55 gallon. we caught him with a container we had in our kitchen that also had a snap on lid to avoid any damage. it also had a pop open lid to allow some air flow. all went well, much better thatn wat we had been expecting :dance