Originally Posted by tismfu
Every time I have tried to use a kiosk after printing a BP (to add a bag), it has rejected me, printed out an information slip, and directed me to see a real live agent.
There is now an option to "Reprint Boarding Pass(es)" (as well as "Check Bags Only") with the new software on the kiosks if you've already checked in. I'm not sure if it allows seat changes however.