Boot with bad superblock in root fs

[Jay Cliburn]

Is it possible to boot a Linux system that has suffered unfixable 
primary superblock corruption in the root filesystem (ext2)?  I know the 
mount command can be supplied an alternate superblock with the sb 
option, but AFAIK, the earliest this can be done is by setting the 
option for the failing partition in /etc/fstab.  But of course, root 
must already be mounted for that to apply.

Is there any Way to specify an alternate superblock to initrd to mount 
the root filesystem?

Thanks,
Jay