PPTP users and Captive Portal users in FreeRadius (mysql)

Hi,

I would like to set up and use m0n0wall together with FreeRadius. I
would like to use FreeRadius to authenticate PPTP users and users in
Captive Portal. Ideally I would like to store the users and their
properties in a mysql database.

Since I am comletely new to the Radius concept, I would like to know if
someone on the list has done this before and if there are any nice
howtos on the subject.

Additionally I would like to ask if it's possible to have one FreeRadius
server serving multiple m0n0walls if the user databases are different?

TIA,
Mikael