We are currently using our RADIUS server to do one thing. It is
authenticating wireless users via Mac address through access points.
Very clean, very simple. We would like to increase the security a bit
by having the users authenticate against eDirectory as well.
RADIUS doesn't work like that. It authenticates a user session... once.
To put it another way, read your NAS documentation to see how to
configure it so that it authenticates both MAC and user through RADIUS.
If it doesn't say it's possible, then it's not possible.