I have a government client that demands that all X-References are bound. They recently expanded this to include attached image files. I just told them you can't bind an attached image file, when a smart-pants engineer in my office suggested that we just paste images in these files as OLE objects. They go static when they loose their reference but remain in the CAD file with nothing showing in the X-Reference manager to bug picky clients.
To paste as an OLE object, copy your image to the Windows clipboard then select "Paste Special" and select the OLE option.