The way that has worked best for me is to connect with telnet but only to start up a xterm displaying to X on my laptop. At one point I did tunnel it through SSH, but in a rather roundabout way: running ssh -R to port 6000 on a server on the same LAN as the A/UX machine, connecting to local port 6000 on the display machine. Worked great!
I built X11R6 and use that, but the X11R4 xterm also worked the last time I tried it.