Windows 2008 SSTP VPN trouble

Hi all,

I've the following scenario:

1 Domain controller Windows 2003 Server R2
1 "VPN" Server Windows 2008 SP2

I've Certification Authority on my DC, by now this CA provides
authentication for the Outlook Web Access (form based authintication) and
for the Actyve Sync for some PDAs.
I want to deploy a Windows 2008 remote access server with SSTP protocol.
My "VPN" server has 1 nic, I have an hardware firewall (Cisco) on the
perimeter network.
All the documentation I've found describe a scenario with a VPN server with
two nick and a fresh installation of a CA. Is it possible to deply VPN SSTP
access in my scenario?