Instead of inserting an image object, create a field object. On the formula tab specify the file path and make sure you tick Return As Image File.
For example on the Formula tab the return value might be:
The logo's should be generally of the same size and width. Expand the field object by dragging with your mouse to indicate the area that you want to draw in.
(This is also how the Catalog Wizard templates can support catalogs with customised images on them.)