[Fedora-packaging] Unsponsored Comaintainer?

Hello, I'm new the packaging thing. I've been reading through all the rules and guidelines, and preparing some new packages to submit. I was wondering if it's possible to become a co-maintainer on an existing package if you're still unsponsored. I've spoken to the current owner of the package and he's more than happy to have me help out, but I don't know if I have to submit my own package for review and become sponsored first. Thanks, Rich Mattes