While working on Pimp my Rom's bew beta, I came up with a way to grant init.d support to any device, which happens all on the app side, no need for install-recovery.sh (or any other file) modifications.
The concept is very simple but it's what makes it powerful and truly universal :
Using Android's BroadcastReceivers mechanism, the app detects whenever the device is rebooted, and when it does, after the boot is completed, it will execute all the scripts inside /system/etc/init.d automatically.
I also refined the kernel init.d support testing, it now requires a reboot but will really detect if the user's kernel has init.d support by creating a simple init.d script that creates a file on the sdcard, and after the reboot, the app will check if the file has indeed been generated, if it does, the kernel has init.d support so the app is useless, otherwise, it doesn't.
Finally, I added options to manage the init.d scripts (edit/delete/run), and will probably soon add an option to select your "init.d" folder (i.e make it so that /sdcard/newinitd is considered as /system/etc/init.d and the app will execute all the scripts in it instead of in the real init.d folder).
The standalone app is fully open-source, so if you want to fork it/add it here/modify it to your needs, go ahead, it's yours : http://github.com/Androguide/Universal-init.d
I attached a signed apk to this post.
Here are a few screenshots :
Also, I wanted to ask you some help ;
I could definitely use your bash knowledge for a new project I started, which allows to flash zips without using a recovery, if you got time, please go take a look and tell me if you see any mistake or better bash translations of updater-script commands. (thread here)