Here is an apple script application for anybody that is still looking. It will work on 10.4 10.5 10.6 and 10.7 and can be run while the computer is booted.
WARNING! This application will delete the entire contents of the currently running user and reset the computer to launch the setup...
I was trying to install a test enviorenment of leopard server on my external hard drive and it told me that It could not install it becuase it could not find a current operating system. What do I need to install before I can install leopard server 10.5?