for getting client cert, you can do on network level, use either wireshark or MS network monitor.
For the default user,
check what acl your “default” user has, and check the acl of the service the client is reaching. if the default user already have the privilege to access that service, it won’t try to authenticate the client, just use default user directly.
#webMethods#webmethods-Protocol-and-Transport#Integration-Server-and-ESB