By default, the InterMapper service listens on all interfaces (INADDR_ANY).
However, if you launch intermapperd/InterMapper.exe from the command line, you have access to a set of switches including
Listen only on the interface with the specified IPv4 address. Disable IPv6.
ref: InterMapper User Guide, Reference section, Command-line Options for InterMapper
I tested it, and it applies to the web server as well as to client connections on the InterMapper server process.
Mike Maki, InterMapper Support