How to make a usable dmg image for Mac OS X with NetBSD?

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

        hello.  I have a friend with a Macintosh computer running Mac OS X
with an external hard drive that took a partial dump, rendering it unreadable
on the Mac.  I was able to plug it into a NetBSD-5.x box and recover the
first HFS+ partition from the drive, but because the partition contains a
bunch of time machine backups, our HFS driver isn't able to read the
filesystem without panicing the system.  My thought for getting things back
to the Mac is either to relabel the bad disk to include a partition table
in a form the Mac can read or to provide a dmg image containing the dd'd
filesystem.  Unfortunately, I don't have a Mac on which to construct this
mess.  So, I'm wondering if there's a way to use NetBSD tools to create a
dmg image containing the filesystem in question, or, can I partition a hard
drive with NetBSD and have it read by the Mac?
Any pointers to documentation or tips would be greatly appreciated.

-thanks
-Brian