minimal console getty that can run any process
rungetty might be the getty you were looking for. It is able to run any program, not just login. If a different program than login is used it usually is run as nobody:nogroup, or the user/group specified on the commandline. rungetty can even be configured to autologin, under certain circumstances. See the manual page for more information.
You have to change some lines in /etc/inittab for having any effect after installing the package. rungetty is based on mingetty and therefore not suitable for serial use.