Hi Doug,
there is no extra permission needed. As said above ovirt-web-ui project is open to all registered Zanata users. One just need to be a member of language group of language one wants to translate.
In this case probably Brazilian Portuguese [1]. Please follow the link and request a language group membership [2]. This request needs to be approved by pt-br language group coordinator. The approval usually comes in days. Once a user is a member of a language group, (s)he can edit translations of all open projects in Zanata, including ovirt-web-ui.
[1]:
https://translate.zanata.org/language/view/pt-BR[2]:
http://i.imgur.com/L9M1hlW.png