Back in Unity 2.6 I was able to embed the activeX Unity web player into Adobe Director and pass data from Director to it, though can't remember off hand if it was possible to send data the other way.
There is no specific documentation to my knowledge for this, but being activeX the (minimal) exposed interface is easy to access.
From memory there was no direct connection to the Unity API,but the interface being web plugin focused did allow for a method of transferring data/instructions, I suspect in the same way that a web page can communicate with the Unity player. However it required code in Unity to then act on that data/instruction, bit like an event manager.
So its defiantly do-able, question is, would it be enough for what you need. My advice download the free indie version and give it a test. Though you may need to install the web player separately to get access to the activeX component, not sure if its included in application installer.