[expert] How? Convert my Dialup Server from Scripting to PAP?

[Edwin Casimero @PLUG]

I'm running a Mandrake Linux 6.1 and a Redhat 6.0 (2 boxes)
as dial-up servers.  My users still login the scripting way.
( as in username <enter> password <enter> /usr/sbin/pppd
<enter>.
I want them to login as PAP.  How do I do that?

Thanks