The answer is yes, you can.
--this gets the web module MBeans loaded in JBoss--
/opt/lib/jboss-4.2.3.GA/bin/twiddle.sh -s <--ServerIP-->:1099 query 'jboss.web:*' | grep "type=Manager"
--Once you have that you can get the active sessions from that MBean--
/opt/lib/jboss-4.2.3.GA/bin/twiddle.sh -s 172.16.0.216:1099 invoke "<--MBean-->" listSessionIds
--And finally, once you have that list, you can pick out the session of interest and expire it--
/opt/lib/jboss-4.2.3.GA/bin/twiddle.sh -s <--ServerIP-->:1099 invoke "<--MBean-->" expireSession <--SessionID-->
You would replace <--ServerIP--> with the ip the server is bound on...it need not be local. This can be run remotely as long as you have access to port 1099.
<--MBean--> would be replaced with one of the results of the first query.
<--SessionID--> would be replaced with one of the session ids from the second command.
Also you would replace /opt/lib/jboss-4.2.3.GA/bin/twiddle.sh with the location of twiddle on your machine. It is included in JBoss.