When you first install ZCO, you can use the ZmCustomizeMsi.
js command to set things like server and port initially (-sn and -sp parms). Since you've already installed ZCO, you can update the registry yourself to get the initial config settings. Each new user would still have to create a profile the first time he/she logs in, but the server and port would already be set. [The email addr in the config tab defaults to the USERNAME system environment variable, but you can just override that when you config].
The way ZCO works with the registry is that HKLM\SOFTWARE\Zimbra holds the settings for all users, and HKCU\Software\ZIMBRA holds the settings for individual users. If you want each user to default to a given server and port, you use regedit to update the following values in HKLM\SOFTWARE\Zimbra:
ZimbraServerName
ZimbraServerPort