Bootstrapper Crash Need to Backup FileVault Home Folder Before Rebuilding

Question

Bottom Line (yes repeated at the bottom ;-))
How do I mount the sparse bundle (FileVault created) from the limited resources available on the OS X install DVD so I can check the integrity of contents, or even just copy the contents unencrypted?
I may just take this into the Genius bar, assuming the correct Evil Genius is available, but if I can get help here it will save me the drive across town.
Background:
Power fault and a hard shutdown, now my iMac won't boot.
Backup of Home folder is about 3 months old using Backup utility (no lectures please, long story)
I would like to backup what I have before doing anything dramatic (like erasing the drive and starting over)
I am using FileVault, which I suspect will complicate things (albeit the backup I do have is unencrypted and in the safe) and was able to copy most (but not all) of the sparse bundle.
I.e., I believe both the system files and my home folder have issues.
I would be satisfied with even an unencrypted copy of the files in the home folder (FileVault sparse bundle), but I am having trouble backing anything up (I/O error, which may mean that a band inside the sparse bundle is corrupted as well).
Possibly Relevant Details:
Single User Mode (i.e., via Command-S) does not reach prompt
Instead I see several "disk0s2: I/O error." with the error details followed by "The system bootstrapper has crashed"
It does point to the specific file issues, but at this point I am less concerned with the system files than I am with the Users home folders (mine and the kids)
Using the OS X DVD and launching Disk Utility the repair disk does not work (even when repeated, which has worked on other disks before).
Invalid sibling link on Verify followed by Invalid node structure (fails trying to rebuilding the catalog b-tree... invalid node structure and invalid record count repeated several times followed by invalid key length, then repair gives up.
Disk Utility unmounts the volume and won't let it re-mount.
Managed to re-mount by forcing the drive to be the start-up disk (Power On with Option key) and then re-started again from the DVD.
Could not figure out how to force the mount from the Terminal.
Again, running from the DVD and then using Terminal I can see the volume (../../../Volumes/Macintosh\ HD) and what appears to be the contents.
On a whim I tried to copy the Users folder to an external drive and then saw the error message about the FileVaulted sparse bundle (file .mtkessel in Users)
Copying the kids home folders this way worked, so the only problem appears to be my home folder (which is a sparse bundle).
Specifically, the "I/O Error" reported by cp is in .mtkessel/mtkessel.sparsebundle/bands/1 and 10... all of the other bands and the related Info and token objects copy just fine. I suppose it is possible that those bands are ones slated for reclamation at the next logout, but I can't be sure.
So I suppose the question is how do I mount the sparse bundle (FileVault created) from the limited resources available on the OS X install DVD so I can check the integrity of contents, or even just copy the contents unencrypted?
Thanks in advance on this ugly problem...
mk

Answer 1

It took many hours to copy the FileVault sparsebundle (both size and device issues I suppose), but I managed to re-assemble it, including the "Rescued Items"; I just used the unix cp -R on the sparsebundle file to force the copy to report the I/O errors... about a dozen or so of the 9000+ bands are damaged.
Could not really tell if anything other than the "Rescued Items" were missing since bands can be deleted during normal use.
I then attached the sparsebundle (which is encrypted) with a shadow (i.e., this sparsebundle is not mountable)
This is the command I used from the directory containing the COPY of the sparsebundle.
hdiutil attach -encryption -noverify -ignorebadchecksums -nomount mtkessel.sparsebundle -shadow bundle.shadow
I am not entirely sure, but the shadow option allows read-only behaviors on the device to be circumvented by allowing write through the shadow...
Enter the password and then I had he "device" appeared in the dropdown menu in DW and then I was able to re-build it.
Then in Preview I was able to see a fully mounted device from which I have started copying. The damage was "easily corrected" according to DW. It may take several hours to copy as well (this time probably due to the decryption as it copies)
I am starting to experiment with the Mail import features to see if I can recover the e-mails... my first attempts of importing from both Apple mailboxes as well as mbox format did not work. And, simply copying the emlx files into the mbox destinations does not work... The items simply don't show up in Mail... I am sure I will figure it out eventually, but  any advice on importing the emlx files would be much appreciated!
mk