Can I restrict the ports that IDMU uses for it's server for NIS
function? I'm having REAL trouble with my firewall, and I DON'T want
to use Allow All Any/Any TCP and UDP.

If not, does anyone know of any specific ports I could open to make
this work?

IdMU ports are dynamically assigned at every restart of the Server for
NIS and there's no way to have it bound to a fix port.
You can use a batch file to determine what ports are being used and
then have the firewalls rules modified using this information. I can
get you a script for Windows Firewall because its rules can be
modified/created using netsh command line. If your firewall allows
editing rules from a command line, you can follow the batch file and
modify it suitably.

- Ashish