How to log on as orcladmin with WNA?

Finally have WNA working, but now there is another "problem": how can I login as orcladmin (or any other user, for that matter)? Because every time, I switch to anything administrative on my oiddas page, Windows Native Authentication kicks in, and presents me with less privileged pages.

The only workaround I have found so far, is to disable WNA for the time being.
In IE, it is located in the Advanced Options (Enable Integrated Windows Authentication, under Security), under FireFox, you would have to remove the Single Sign On server from network.negotiate-auth.trusted-uris, in the about:config.

If anyone has another solution, please comment!