[Users] how to add custom certificates to windows messenger 5.1

Hello openser users, I am trying to connect windows messenger 5.1 with openser in TLS mode. OpenSER uses the custom created certificate and predictably windows msngr returns -------------- There was a problem in verfiying the certificate from the server. Please contact your network administrator. -------------- I do have my own client certificate and ca-list created with openser scripts and I would like to add it to windows messenger to verify the server certificate. Is it possible to add a ca-list to windows messenger so that it can verify the server certificate. If yes, kindly point me how ? thanks and regards, Pjothi