IMHO, the person who came up with the default 'public' and 'private' community names should be shot right after all the developers/engineers who design products that ship with these names enabled by default!.
That said, you should be able to use SNMP to get stats off the box. If I remember rightly you use the base station password as the community name.
That said, don't do this unless you're using WEP or are running MRTG on a hardwired system (i.e. not over the air). SNMP queries (including the community name) are sent in plain text and is too easy to snoop. Since it is the same as your base station password, it's like giving your network keys out to anyone who's passing by.
On the other hand, what problems have you had with MRTG and your Cisco router? I've never had a single problem with that.