BW, have you tried moving the change mat onto the bed? You can sit by him that way. Otherwise, get out everything you need first and leave the drawer shut from the side of the drawers.

I hate to be the bearer of bad news, but nappy changing does not get any easier when they start to move around! We started doing DD's on the floor and I would sit next to her, since lifting up and down and worrying about her wriggling off the table got too stressful!