here are a couple of things we've done in my old offices:
- soda can door: get every aluminum soda can you can and cover the entrance to his office/cubicle so that he cant get in. do this during lunch time...have someone take him to lunch and a group of you do this...its a female dog to take off.
- take a few pieces of bologna and tape it under his seat. after a few days, hes gonna smell some serious funk, but hes not gonna know where its coming from. after you leave the office, call him and tell him. we did this to one of our coworkers and he had maggots growing from his seat. we had to get him a new chair, but it was so worth it.