manually run export.php

I cannot log into wp-admin and need to do an export of my data so I can do a fresh install. I need to run” http://www.domain.com/wp-admin/export.php but I need to bypass the checks in place seeing if you are logged in or not. (as this is where I have problems.

Is it possible to run the above script without signing in, what pieces should I comment out to be able to do this?