Hi Robert,

have you tried the Graphic Converter for Mac? It's the best proggie you can use for these "missing BUM-file issues".
Just go to this webpage:
http://www.lemkesoft.com/en/graphcon.htmI use it all the time to convert my *BUM.jpg files into *BUM.bum files. There's also a batch utility included which helps you to convert several files altogether.
If you have further questions just send me an IM or email me under nonhuman-being@gmx.net

Hope this helps,
Phil