Check out the editor/filemanager/browser/default/frmresourcetype.html file in there you have an array of the types. In addition you will need to change you fckConfig.js to set the default type for the Link and Image browsers, this is done by changing the type=*** bit on the FCKConfig.ImageBrowserURL and FCKConfig.LinkBrowserURL configuration variables. (the Link browser one you will need to add the &type=** bit
You may also need to change the internals of the connector depending on which one you are using. For my version of the php connector you can do this in the config.php file, there is an array of the accepted types + you will need to add the type specific config options for your new resources types.
RE: Change names of file browser types
You may also need to change the internals of the connector depending on which one you are using. For my version of the php connector you can do this in the config.php file, there is an array of the accepted types + you will need to add the type specific config options for your new resources types.