If its showing port channel 1, that means that the user is connected to another switch upstream on portchannel1 (L2 Etherchannel) you need to get on whatever switch is on the other end of channel1, and run the same command until you get a normal access fast ethernet port with a single mac-address on it.
Unless your running ciscoworks or some other SNMP monitoring software which keeps a logs of end users and switchports, there is no quick or simple way to find them.