EAP-PEAP with "special" users

[Jonathan Gazeley]

I've inherited a manky old RADIUS server and I'm trying to get to grips 
with it.

In short, it is using EAP-PEAP/MSCHAPv2 to authenticate users against 
Active Directory. This is all working fine.

I want to add some test user accounts that can be authenticated through 
EAP but use a flat file rather than ntlm_auth. What's the recommended 
way of handling this without harming the performance of the majority of 
the users who will not appear in the users file?

Thanks,
Jonathan