AIX and radius authentication

We want to use RADIUS to authenticate our AIX server logins. Can anybody tell me how to set on AIX server up to use a Radius server to authenticate or point me to documentation on setting up AIX to use Radius to authenticate user login.
Our problem is that we have a few users that access our AIX servers and will be going to 30-50 users and want quick and easy way to allow them access without having to create 30-50 new user account on our 50-70 AIX servers. We researched using AD but have issues with scheme creation as AD is controlled by another group.

I don't know about RADIUS, but I would suggest LDAP as an alternative. Try this IBM redbook:
IBM Redbooks | Integrating AIX into Heterogeneous LDAP Environments