A kiosk mode is running an X session where anything that can be disabled witout problems is disabled - But not more.
That's the perfect case where it makes sense to just jump into the code itself to learn:
It's a collection of scripts, most simple, connected in a simple way,
and you need to find you way throught the code anyway to build the kiosk mode.
Take a look at
/etc/X11/Xsession - it runs the separate scripts in
/etc/X11/Xsession.d at the end in their order, if they are not marked as disabled by a name change to indicate that. Then just got through all the scripts:
Many are trivial stubs, basically empty. Some are complicated - but not relevant to your use case. So there will noy that much code be left you really need to read.
$ ls -l1 /etc/X11/Xsession
-rwxr-xr-x 1 root root 3730 Mar 22 2012 /etc/X11/Xsession
$ ls -1 /etc/X11/Xsession.d