First off, I'll be asking my corp if they mind my alt joining this, if they don't mind, I'll sign up as soon as I can. I think they might be a bit hesitant about that though. So if they do mind it's a bit of a problem, but one that can be easily catered to.
Basically, if I can't join, I won't be able to see what you're all saying in Corp Chat. So if you keep the current public chat channel for all your general talking, I'd be able to hang in that with my characters. I know security is a problem, so you can keep all your fleet notices and intel in the Corp Chat. That way you won't be sharing private information with anyone outside the corp, but can keep up with people who can't join your corp for whatever reason.
The way E-Uni does it is that they put a password on the public chat channel, with the password available from their forums. So you could post it here for anyone interested in joining that chat. Or maybe keep it with someone who has to be convoed for it, and then credentials provided.
I'm sure there are others in the same position. I can see there are a couple of alts joining.
So yeah. If you could keep general chat in a public channel, and intel and fleet movements in the private corp chat.