There may be a couple different options short of having to log in programatically. The first is to include the username and password into the URL like so: http://DOMAIN/Orion/Login.aspx?AccountID=USER&Password=PASSWORD. You should be able to use that with any of the URL's for the site to allow direct access. The second option is to enable the DirectLink account. It's a specially named account that is used for when you access a page directly, "skipping" the login. There should be more info about it in the admin guide.
Hope that helps.
Thanks, ultimately I was able to get the C# code to work, but your suggestion got me headed in the right direction.