Perhaps an easier way of accomplishing this is by using
ANSI.SYS and the "$e" paramater of
PROMPT.
Add "
devicehigh=c:\windows\command\ansi.sys" (or c:\dos as the case may be) to your
config.sys
now reboot and try typing "prompt $e[
31;34m$p$g" and see what happens.
See the
ANSI colour codes for more details.