It might be a permissions problem with the script that you are using:
Why can't this script run after logging in? You could put a line in .bash_login to run a terminal with your script.
Because of the handoff from root booting to user login, this might be difficult to do without breaking something.
A less elegant way of doing it is to change runlevels, start with runlevel 1, run your script and at the end of your script, change to runlevel 2. But again, I would expect breakage.
tgalati4@Mint14-Extensa /etc/init.d $ apropos runlevel
runlevel (7) - event signalling change of system runlevel
runlevel (8) - output previous and current runlevel
startpar (8) - start runlevel scripts in parallel
telinit (8) - change system runlevel
Tell us what your script does, there may be a better way to perform the task than changing runlevels or running in tty2.