I have built an internal account to test custom roles on but I haven't been able to figure out a way to log out of my passed-through windows account.
I feel like I am missing something...
Use this URL to get menu where you can choose internal or windows authentication
http://<your NS server address>/Altiris/Console/Logon.aspx
As far as I know, internal account authentication doesn't work in 7.5 release
Did those suggestions help? If so, please mark as resolved.