ispconfig3 and vpn setup per user

I am going to setup a new isp3 (fedora 10 or centos5.3) box but the issue is that the box needs to also function as a vpn server (pptp is fine) for outside windows users to get into the network. What I would like is the ability to control which users have the vpn access and which do not.

Is there a howto for this already avail?

-T

 

I don't think we have such a tutorial.