IIgs Hard Drive Woe - directory missing

[mouse@Misty.com (Mike Kelly)]

Hi everyone.  I went and did something stupid a few hours ago.  I was messing
in ProSel's disk block editor, and I intended to try to fix a corrupt block
on my 3.5 disk.  Unfortunatly, I wrote to the /System partition of my hard
drive.  Worse yet, I blew away block 4, which contained the directory of the
disk.

So no data has been lost - but it's not a valid ProDOS volume anymore.  I
went on IRC frantically, and someone told me I might be able to use Salvation
Deliverance to fix it.  Does anyone out there have this program, or know of
some other way I can fix this?  (I can get into Finder / other useful stuff
via bootup disks, and my /application drive is fine..)

-- Mouse (mouse@misty.com)