dmg handling

[Zoran Kolic]

Howdy!
I got a file made on mac, sized at 142 mb and with
dmg extension. It is a dump of 4 gb SD card with
firmware upgrade files. File says:

  disk1s1.dmg: VAX COFF executable not stripped

So, compressed. The file system on that original
card is ext3. Linux people use dmg2img utility to
decompress and then mount it with options like:

  mount -o loop -t hfsplus image dir

If correct, I could try to bunzip2 it first, then
rsync to sheevaplug node (ubuntu on it) and mount
finally. The final step would be to write that ima-
ge to new SD card and use it to upgrade the gadget.
I was sure that simple dd would suffice, but more
I read, more I see it's wrong.
I also assume that I cannot write that image to
smaller, 2 gb SD card.
Any idea what to do in this situation?
Best regards

                       Zoran