OWA/OMA, SSL VPN and Radius Accounting

We have implemented OWA/OMA via SSL connectivity on a Windows 2003 server. It
is fantastic!

I want to be able to log the SSL VPN connections, so I can see the usage of
the services. It seemed simplest to do it by logging them in the same way as
I log the standard PPTP/L2TP VPN connections on our separate MS VPN server -
by using Radius Accounting on our IAS server.

I just can't find a way to log the SSL connections to a Radius server. Does
anyone know if it can be done, and if so how?

I would much prefer to use Radius accounting - but in the mind-boggling
possibility that MS have not implemented this, do you have any
recommendations as to what the best way is to get database reports of usage
of this service is?