Tell GRASS to use fewer colors?

[spf at hoqaa.att.com]

Hi folks,
  An issue I've been talking about for awhile is coming home to roost,
so I thought I'd see what other folks have done about it.

  We have our own software do animation on top of the GRASS monitor.
But, since GRASS (by default) uses all 8 bit planes, we can only do this
by employing XOR drawing techniques, which yields only one "color" (which,
for any given object, is dependent upon the background).  We'd like to
have a few colors for ourselves.

  It would seem straightforward to tell GRASS that it has, say, 64 colors
instead of 256, thus retaining 2 bit planes for our animation.  Has
anyone tried this?  Does it really free up two planes, or just cause
a portion of the table to be unused?  As usual, I'd like to benefit from
others' experience before burning up time on this.

Thanks!

Steve Frysinger