[iPAQ] Modification of startup?

Hi again,

Can anyone please explain to me how to modify the startup script.
For example I want to start Microwindows or any other app at the start
after the kernel boots, how do I do it?

I know that the file 'linuxrc' has the following line at the end:

exec /sbin/init

I know that the file init executes the startup. But how do I modify it
and make changes.

Thanks,
Sri.