changing the inittab file to use rungetty instead of getty
In some ways the neatest thing to do is edit /etc/inittab in the chroot.
The sed scripts in the CASPERGETTY part of 25configure_init try to
be so tight that they only rewrite the original debian /etc/inittab. I
can't vouch for the intent of the code outside the CASPERGETTY
block... however I think it is a bug if that code rewrites modified
versions of the original debian /etc/inittab. There may be come ubuntu
copat code in there too but I don't know about that.
(1) I'd try to modify the /etc/inittab in the chroot first and report
bug 25configure_init overwrites it.
(2) yes you have identified the right part of the code which rewrites
/etc/inittab patching this file will also do what you want.