I first want to say that i love the stuf you guys are doing! I want to use a computer as a frontend and like to boot from a cd/dvd so that the computer doesn't need a hardrive and will always start properly. If i want to do that i must implement my own specific backend properties and X11-config. Is there a way to edit the iso and recompile it afterwards?

Theoretically it can be done. You could google for 'knoppix remastering' and search the forum for 'remastering'

Or better yet, search the forum for prep-ts and use the terminal server to network boot your frontend. Then you won't need to insert and spin up the cd every time you want to boot.