[CentOS] One for the Cisco experts...

I have a Cisco 6509 switch that I'm monitoring with SNMP from a
CentOS5 machine.  SNMP polls are the only access I have to this
device, we are not allowed to log on via telnet.

How can I find out which port on the switch a particular server is
connected to?  I was hoping that this is somehow possible using the
mac address and the data gathered from snmpwalk/snmpget requests but
I'm not having much luck.  How would you tackle this problem?