How to add a script to LiveCD shell

[NiceGuy]

Hello,

Not really sure where to post this one ... "Kernel" ... "Programming" ... or "Other Things Gentoo" .. so I chose the later. Anyway my question may or may not be exclusive to Gentoo so I apologize in advance.

I have been hacking around with the minimal 2007 Gentoo LiveCD for quite some time now ... I am interested in having a script of my run automatically .. but after the LiveCD has completed normal bootup and additionally brought up the command shell.

To clarify, imagine inserting the LiveCD ... booting normally ... the shell comes up normally (remember this is a minimal LiveCD so ... no GUI or login prompt) right after the shell comes up and is presented to the screen ... my script would then be run.

I read up about startup scripts ... but those generally occur before the command shell gets presented so are exactly for me.
Thats it .. thats my question.
Hope someone can help
Thanks

Additionally, I am curious as to what process starts the initial shell ... is it started in kernel or in the /sbin/init executable? or somewhere else?
Thanks again