[bleke]

Yes you can and start whatever program you want, take i look at better-initramfs (https://github.com/slashbeast/better-initramfs), although it is more for gentoo/funtoo.

Basicaly when linux boot from initrd it starts "/init" executable and chroots to your system (ok, it is using pivot_root and it is slightly more complex), but idea it is same as manually mounting filesystems and doing chroot then starting executable /bin/init

[gh2k]

There's also an example script on the Gentoo wiki that might serve as a good starting point: https://wiki.gentoo.org/wiki/Custom_Initramfs/Examples#Simpl...