I posted on this issue some time ago.

I have a Quadra 650 with 32MB ram and NetBSD 1.3.1 installed.
X runs fine with the OSFA server and I've even managed to compile and
install Lesstif.
The standard Xterm has its own "terminal functions" and in addition can
emulate VT100,VT220 and a Textronix terminal it you give it the right
instructions (on startup for the VT220). This is all in the man pages.
I've also seen a few other specialised emulators on macbsd.com. However I
need a Wyse60 emulation. Has anyone seen one or know how to add one to the
Xterm (the man pages say that it is possible to add other emulations
(widgets) but the program needs a rewrite to make it more modular and
extensible).

Why Wyse60 well my mac is at work and our host system expects to see Wy60
terminals. My MacOS emulator (MacEmulate) does the job but I would like to
spend as much time as possible in UNIX, ie all day not just a few
intermittent slices of spare time.

Regards
Richard