Mac OS X install question using target disk mode

Ok so I made the mistake of putting my powerbook G4 into target disk mode and then trying to reformat the drive for a fresh install of OS X, why you might be asking? I am not really sure either. I have a "updated" system disk which was a single user of 10.4.6.

SO the powerbook does not start using the 'c' button with the system disc in traditional way. I have put the powerbook into target disk mode and my mini reads it as an external firewire. I have even installed OS X on this drive (apparently can only boot from it using my mini).

My real question is: How can I get the computer to recognize the installed OS as the 'OS' to start up from? Any ideas?