Hello,
Thanks for stopping by. I'm not sure if that's possible once it has been installed. Just out of curiousity, why would you want to do this - Gingerbread is the latest Android version that most, if not all devices have now.
(Thinking)
I'm not quite sure if "rooting" the device could make this possible. Maybe someone who is familiar with the rooting process might chime in to help.
Good luck.