Forwarding to a non-standard port

[Kris Kennaway]

Is there any way I can forward queries (in, say, a forward zone) on to
another server listening on a non-standard port (under BIND-8.2)?

My problem is that I would like to implement two servers on the same
machine, one (on port 53) which is queried externally from the internet, and
also forwards internally-originating requests onto the other server process
listening on another port. We only have one server which is well-suited to
acting as a DNS server, so I need to have them both on the same machine.
Forwarding is needed because of the difficulty of updating all of the
internal machines to point to the second server directly.

If this isn't possible, could someone in the know point me to the relevant
part of the source code where I might look to hack the request forwarding
code into doing what I want?

Thanks!
Kris