UCMA and the Lync Server SDK behind a web application

I have a situation where an agent will be using a web application from the same computer they have the Lync client running.  I'd like them to be able to control their conversations through the web application or their Lync client.  I'm trying to find a way to do this that is both PC and Mac friendly and does not require custom software installed on their desktop.

Some of the specific scenarios:

1. Answer incoming calls through the web application.
2. Report the state of any in-progress calls in the web application (active/on hold and duration)
3. Place an active call on hold/retrieve from on hold from the web application

Is this doable?

Thanks,

Corey