Enable standard winforms app to use ClickOnce?

Hi

I have taken over a winforms application that is currently installed on some client machines.  At the moment whenever an update is done, each computer has to be updated individually by overwriting .dlls. 

How can I enable this application to utilise ClickOnce for updating?  Do I have to uninstall the current applications and publish the application as a ClickOnce application and re-install on client machines or is there a simpler way?

Many Thanks