[Zope-CMF] ?how to override default content-type when putting files with FTP

[Tim Hoffman]

Hi

I am building a CMF site, with a number of customized (ZClass based for 
the moment)
Portal content types.

I will need to bulk upload images (which have a new Portal type based on 
CMFOptions ExtImage)
which I am calling ArtWorkMedia, the parent Folder is ArtWorkFolder.
ArtWorkFolder is defined to only allows content-types of ArtWorkMedia and
ArtWorkMediaThumbnail, however when I upload images into an ArtWorkFolder
they are uploaded as Portal Image, which is pretty much what I expected 
(though I half expected
an error).

Obviously I have to override the default behaviour/portal_type for the 
images uploaded by ftp/webdav
 but I am having trouble working out how/where I can/should do this.

Could someone give me a pointer.

Thanks

Tim Hoffman