Is there a way to do in FireFox what was easy with IE?

I wants to save a couple cookies but not on the cookies.txt file. I want to remove them from the list to test out what happens if I don’t have the cookie(s), then replace them if it doesn’t work and I need then back. [Still working with Coppermine. I’ve got a couple “headers already sent” errors I need to fix, which I need to have no cookie to see in the first place. But due to the errors, it won’t issue me any new cookies, which I need in order to log in as admin and change settings to help errorshoot]
It was easy in IE, because all the cookies were separate files. Now it’s just this one file, says right in it “This is a generated file! Do not edit. To delete cookies, use the Cookie Manager.”
I tried editing it anyway, and while removing the “cookie” by deleting the lines in cookie.txt, then refreshing the page really does remove the cookie, pasting it back into cookies.txt does not make it work again. In IE, I used to have a folder of “cookies to keep”, so I could wipe my entire cookies folder, then just copy/paste the ones I kept, and I would stay logged in to the sites those cookies were for (ie LJ, hotmail, etc).

Cookie Manager doesn’t have a way to do what I want, you can just Delete Cookies, so is there even a way to do it with Firefox?I found an extension called Cookie Culler, but it just seems to be able to prevent certain cookies from being deleted, not store them elsewhere and import them back and have them work.

(This is really only a slightly preemptive need. Right now I have a cookie, so I can log into admin, and for some reason the gallery displays fine for viewers. That’s really all I need; I can have customers email me photos, like what I do now, and upload all gallery images myself instead of letting customers do it if it turns out I can’t get cookies to work for customers either. I’m just worried about what’ll happen when my current cookies expire (~midnight tonight), because if I haven’t fixed the errors by then (and I have classes today), it probably won’t issue me a new cookie, and then I won’t be able to upload images either. The whole point is to have a gallery that can be updated everytime a customer send me a photo of them in their hat (or, ideally, have a single “customer” login so customers can upload the files themselves, a this might encourage more people to send them in))

Oh – I’ve already tried loggin in using IE, saving the cookie, and using the “export cookies” feature to send it to FireFox. I can’t login in IE due to the “headers already sent” error which causes a “your browser cannot accept cookies” error, so since I can’t login there’s no cookie to export to FireFox.If there’s no way to do this, I guess I’ll just install coppermine separately from the shop. I could have it open in a new window, but it’s still going more “away” from the shop than customers are supposed to go. They’re supposed to hang around and buy stuff. ^_~