Just asking, since that was my telnet client of choice in my pre-X days. However, there is at least one telnet client that is specifically designed for MUDs...

[One quick look at VersionTracker later...]

Actually, it turns out that there are several MUD telnet clients available. I just searched on MUD in the Mac OS section and turned up about five. Has he tried any of these yet. A couple are beta, one is freeware and another is shareware.