Rebooting Directly Into Single User Mode

Hello. Is there some one to perform a full reboot on a node that is in runlevel 5 and have it come up directly into single user mode without modifying grub.conf, inittab, or manual intervention (stopping grub at boot, typing 'single')?

Some of our test systems have poorly coded init scripts that don't properly clean themselves up (which is another issue altogether), so doing the usual 'init S' doesn't always bring the system down to a true, stable state, so a fully CTRL-ALT-DELETE type of reboot directly into single user mode is preferred.

We've experimented with changing the RUNLEVEL variable but are wondering if there isn't an easier way to do this akin to the old Solaris method of typing 'reboot -- -s' at the command prompt.

Thank you,

SC