To boot into single user mode, simply add single
to your boot string...
ie if you boot with lilo and your boot string is Linux, at lilo prompt type Linux single
If you use grub, you may need to press 'c' to go to command line.
As an alternative, from within your system open a root shell and give the command "shutdown now" without -r nor -h... you'll go to single user.
However, unless you have problems related to 2GB boot boundary (i.e. old pc and big / partition) you can simply get rid of /boot partition:
mount /dev/hda1(or whatever) /tmp/boot
cp -a /tmp/boot/ /boot
Now remove your /boot entry from /etc/fstab
If you use lilo, remember to run "lilo" to complete work