There is a version of getty in BusyBox. You launch it from inittab using the keywordrespawn, which restarts getty when a login shell is terminated, so inittab should readlike this:
::sysinit:/etc/init.d/rcS::respawn:/sbin/getty 115200 console
getty: can't open '/dev/null': No such file or directory
$ cd ~/rootfs$ sudo mknod -m 666 dev/null c 1 3$ sudo mknod -m 600 dev/console c 5 1