x:5:once:/bin/su user0 -c "/bin/bash --login -c startx >/dev/null 2>&1"

Starting X as preferred user without logging in

A way of circumventing display managers and boot straight into preferred window manager or desktop environment is the following.
In /etc/inittab change:

id:3:initdefault:

[...]

x:5:respawn:/usr/bin/xdm -nodaemon

to

id:5:initdefault:

[...]

x:5:once:/bin/su PREFERED_USER -l -c "/bin/bash --login -c startx >/dev/null 2>&1"