Here's a pic of a simple but effective jig that another member here, nced (SpringerEd), made to bend barrels. In this pic the jig is positioned to bend a barrel in order to lower the point of impact. The main thing to remember about bending a barrel to raise or lower the POI is to keep the bend going straight up or down. You don't want to induce any sideways bend unless that's something that's actually needed.
Ed, if you see this I hope you don't mind me posting this pic of yours. I saved a copy of it before the Photobucket fiasco with the intentions of making one like it for myself.