Thank you very much WoodyZ & MacsRule for your kind help. This is what I have done:
1. I have installed OSXFUSE 2.5.5 and VMDKMounter 3.1.3 as indicated using Pacifist install. The latter now lives at:
/Library/Application Support/VMware Fusion/VMDKMounter.app
2. Since double clicking the VMDKMounter application did nothing, I rebooted the Mac with OS X 10.8.3 to no avail.
3. Then I found that I could mount the VMware disk image that lives at
/Users/~/Documents/Virtual Machines.localized/Mac OS X Server 10.6 64-bit.vmwarevm
simply dry drag and drop over VMDKMounter. It mounted the disk "Mac OS X Server 10.6.x".
4. Once mounted on the OS X 10.8.3 desktop, Disk Utility 13 could verify it (all OK).
5. But DiskWarrior 4.4 gave the following error when trying to rebuid its directory:
DiskWarrior encountered an unexpected error while attempting to rebuild the directory of the disk "flat".
Rebuilding was cancelled and the disk was not modified.
Restart from the DiskWarrior disk and try rebuilding again. If you report this error, please mention the error code (2150, 5011).
So, is there a way of rebuilding the directory of a VMware virtual disk with Mac OS X Server 10.6.8?
Thanks.