I thought of implementing this the easiest way by setting values for
< authorization>
< allow roles="AppAccessGroup"/>
< deny users="*">
But it didn't work right off the bat, and that was confusing. I also had Anonymous access turned off in IIS, so the browser was prompting me for NT credentials. While trying to figure this out, I had a surprising find here: http://blogs.msdn.com/b/dougste/archive/2006/07/27/680031.aspx
But that fix didn't work too.
After a while it stuck me that it may be the custom role provider and I commented that out, to test. And voila!, it worked.
I hadn't seen anybody mention this anywhere, but sure somebody must have had this issue and figured it before.