Authoring a new Network Device Management Pack for SNMP device (ASA5525x)

Is there any good documentation on creating your own management pack for monitoring a network device that has no support.

We have some Cisco ASA5525X firewalls and would like to have the monitoring show interface metrics, etc.   The generic monitor doesnt give this.

We have the MIB info for the ASA5525X so it would be kool to create our own that will give us the metrics (like interface bandwidth, etc).

Thanks

Lance

Thanks Lance