The following shell script should work for VGA consoles:
for n in 1 2 4 5 6 7 8; do
setterm -fore yellow -bold on -back blue -store > /dev/tty$n
Substitute your favorite colors, and use /dev/ttyS$n for serial terminals.
To make sure they are reset when people log out (if they've been changed):
Replace the references to getty (or mingetty or uugetty or whatever) in /etc/inittab with references to /sbin/mygetty.
setterm -fore yellow -bold on -back blue -store > $1
exec /sbin/mingetty $@