Yes, you can limit bandwidth on a per transport or per user session, as long as you know the IP address you wish to restrict. See the ASA Traffic Shaping & QoS Documentation here:
https://supportforums.cisco.com/docs/DOC-1230
Peer to peer blocking is also possible, but it is a bit more complex. Please read the doc here, as it explains it better than one can do on a message forum. :)
http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00808c38a6.shtml
Rate this post if it helps.
Cheers,
Tim