[ale] Picky, picky: Setting root background under 'Xvnc' and 'mwm'

[johnmills at speakeasy.net (John Mills)]

ALErs -

I'm running tightVnc for remote sessions, and my '.vnc/xstartup' ends by
launching 'mwm'. I would like to change the default root-window background
and haven't been successful with 'xsetroot' until after my session opens
and I issue the command from a console window.

I would like to put my background command either in a resource file 
('.mwmrc' or 'startx') or as a default environmental setting, but so far I 
haven't found the magic.

How should I set this?

TIA.
 - Mills