FCKeditor resource browser: how to set allowed extensions and paths?

I want to set paths and allowed file exnetsions for fck file browser on per-tv basis.
For example, i have a tv for storing a link to graphics file for a magazine. I want fckeditor to be able to access only specific path (where _i_ suppose to keep graphics) and only specific filetypes (valid datatypes are png, jpg and swf for me). If the only way of doing such things is creating a new datatype (by modifying one of existing datatypes), please tell me where i can do this.