Cisco Switch Manager

If there is only one vlan involved, then just set your switchport as 'Access' and to the desired vlan. It will ignore any vlan tags.

If you want to have multiple vlans, then things get more complicated as Evan Anderson alluded to, but even then you might be able to do it (though you might not want to -- sometimes being overly clever has its downsides...).

[edit]

So here is the requested (not) pretty picture. Option #1 is the simple situation where they hand you a connection as a access port, in which case vlan tags don't matter. Just assign your port to the desired vlan.

Option #2 is the more complicated situation where they are handing you a trunk port with several vlans. In this case you can use another switch to "re-map" the vlan tags to your desired numbers. Be careful with this as it a little unusual...

In the "show interface" output, you'll see cumulative counters since the last counter reset ("clear counters []", no specified interface clears counters for all interfaces). This allows you to take snapshots at whatever interval you want. It's the same counters as used by the SNMP management interface (Cacti, MRTG and other monitoring software) and should be relatively easy to parse.

If you're happy scraping the CLI output and do it yourself, that MAY be a quicker way to get up and running with this specific task. I do suspect that some training material and time to install MRTG or Cacti will be worth your time investment, though.