Hi,
The settings for display contrast is not yet available through the menu, but I received some info some time ago about how to do it within VxWorks through the telnet interface on the terminal.
For me, it did not work, but You could try:
EQUTESTREQ 157, "<level>"
<level> 0-7, 0=min, 7=max, 3= default
Best regards
Paal