lpc stop, not root

[Ssi]

Ok, you all did so well with halt not root, maybe you can show me
a simple way to give lpc stop to all users. We have 2 pen plotters
that get brain damage with multiple plots in the Q. 
    The plotters don't return 'home' between plots.
I have a shell scripts that watches the Q and does an lpc stop
until the active plot leaves the Q. Then it does an
lpc start to let the next one out. I don't want to do all the
plotting myself. The gf filters for the plotters are not scripts
so I can't put a sleep in them. One plotter is a Calcomp 1044-GT
the other is a Computervision P1000.
   Someone in comp.periphs gave me a C program, but I have no C
experience yet. Can I change the group of lpc ?? 
                             Greg Ripp Ph (813)628-6100