[Alan Anderson]

Tether the robot after you change the team number switches on the OI. That will "teach" the robot controller the number.

You'll also want to change radio channels on one of the controllers. For the 2005 system, setting the high bit of the team number will let you do that. For the 2004 system, you'll need something plugged into the competition port that can activate the "practice" pin (search the Chief Delphi forums for "dongle"). Then flip some of the channel switches until you power up with something other than channel 40.