Macintosh client connecting to Windows 2003 L2TP VPN Server

I have a Windows 2003 VPN Server setup to authenticate clients via L2TP with
certificates for authentication. There is a certificate authority
auto-enrolling Windows domain computers with certificates. Also there is web
enrollment setup for non-domain computers to import certificates. This all
works cherry except for Macintosh clients.

Importing the certificates into the Mac Key Chain which seems to work. One
is the Trusted Root Certificate Authority importing into the X509Anchors.
The other is the public key imported into Login Key Chain. When going to
setup the VPN client however I get an error stating that no suitable
certificates exist in the Key Chain. Any know how I can setup the
certificates on a Mac to get L2TP VPN client to connect to a Windows 2003 VPN
server?

Thanks in advance,
Brian