SSO Remotedesktop Apps over TMG and Remotedesktopgateway

Hi

Is it possible to enable SSO (Login only at TMG Auth-Form) in the following scenario:

External Client opens Webbrowser and authenticate at the TMG Auth-Form, after that he will be forwarded to the RDWEB Page. <-- SSO to this Point works

When he clicks a RemoteApp there should no Login prompt and the RemoteApp over Remote Desktop Gateway should start with the Credentials entered at the TMG Auth-Form.

How can i accomplish this Task?

Thanks