In order to access resources configured to require client certificate node usually uses certificate from pem file of key as data
One really good example is azure sdk when accessing management api: https://github.com/WindowsAzure/azure-sdk-for-node/blob/master/lib/services/serviceManagement/servicemanagementservice.js#L346
Having a feature to pass in options object referring to a certificate in certstore will make node much more usable on windows platform and azure.