DISPLAY=[machine-name]:0.0; export DISPLAY
This may vary by server. A good way to determine the correct value is to connect to the server via Xstart and then to check the value of the DISPLAY variable.
(Telnet connection via Xstart)
Sun Microsystems Inc. SunOS 5.10 Generic January 2005
$ echo $DISPLAY
10.177.10.137:1.0
