Remote installation through QS when user is a non-admin

I am not able to remotely install the Host module when the remote user lacks local admin rights. Even though the installation wizard prompts me for username/pass, UAC still prompts for username/password – unaccessible for me.

Second: While this is a "Windows only" feature it would be great to be able to start the installation procedure from the Mac client provided the remote system runs Windows. My colleague and I use Macs, but most of our clients use Windows.