Bandwidth used value

Hi all,
I've read through quite a few posts and didn't seem to find anything similar; if you know a thread that governs the same topic, please do direct me there.

I am looking/wanting a script (preferably PHP or Perl) that'd be able to communicate with WHM externally and figure out a certain account's monthly bandwidth used. Is there ways to do that? Or can I do certain crontab command on a set interval (15 minutes or 30 minutes) to pump my current month bandwidth usage into a MySQL table?

Please get back to me on this when you have a chance; I've tried other forums and no one seems to know anything about it...

Many thanks,
Andy Huang