I may sound really dumb here, but the stuff that you are reffering to as "packed" data may be data that is returned in hex? As in teh SYNTAX DEF of a (SNMP Specific) MIB. IE Integer32, IpAddress, Integer, Octet, Hex. There is no other way to match this type of data (besides regex) and unpack it without manually looking in the MIB def file for that specific oid.

Or mabye Im looking at this wierd or somthing.