Firstly, you don't need to create a package - if you want an agent installation package without embedded credentials, then ePO already makes one for you
The default framepkg.exe in the master repository (..\DB\Software\current\epoagent3000\install\0409\framepkg.exe) will do what you want.
You also won't need any switches except /s. (Framepkg.exe effectively has the /install=agent switch built-in.)
Finally, please *don't* use the /forceinstall switch unless required - it's not intended for general use, but only for situations where the normal install fails.