getting additional functionality, snmp or external program

I think this is possible, but wanted to make sure and ask what would be the best way to do this... ie. Execute an external program or create a module. I'm authenticating cable modems using freeradius with a sql database backend. What I want to do, is after the authentication process, query the cable modem using snmp (retrieving data) and store this data back into the already connected database. Is anyone doing such a thing? Thanks, Duane