This is reviving a very old thread but I just received this ornament for this Christmas and although it says it is not Mac compatible, I did find mac software on the manufacturer website.
At senario.com, look for the Vu-Me product (which includes picture ornaments). There is a link to a website with both mac and windows sofware.
www.vumedigital.com
I installed the mac version and when you launch the software it doesn't seem to do anything but you can browse your drives for photos, click the right arrow to transfer them to the device side and then when you click the circular arrows (like a refresh icon) it transfers them to your ornament.