Ah, OK, now I understand what you're trying to do.
I'm curious though: how did you get it to work with Feisty? There was a bug with Feisty, more difficult to work around than this one, that also didn't make persistence work.
Anyway, I'm afraid I don't know how to help. Even if you have the new initrd.gz, you cannot replace it on the CD, so I think you're stuck with this bug and unable to work around it. You'd have to do with Gutsy until this bug is fixed in, say, 8.04.1.
Ah, OK, now I understand what you're trying to do.
I'm curious though: how did you get it to work with Feisty? There was a bug with Feisty, more difficult to work around than this one, that also didn't make persistence work.
Anyway, I'm afraid I don't know how to help. Even if you have the new initrd.gz, you cannot replace it on the CD, so I think you're stuck with this bug and unable to work around it. You'd have to do with Gutsy until this bug is fixed in, say, 8.04.1.