Brushless airsoft guns?

[BL_RV0]

Is this even possible? I'm thinking of upgrading a airsoft AEG to brushless/lipo power somehow. Can this be done? I was thinking of using a servo tester with my trigger mounted to it to activate the motor. I was also wondering what size motor these guns use. Looks fairly small, here's a link to one:
http://www.airsplat.com/Items/AC-UPI-ICS-MC61.htm

Thanks y'all