Viewer API - How to highlight a node via it's instanceID

Given an object instance id, how can I acquire the actual instance of the object so that I can supply it to the ‘assignMaterial’ method?

I’m able use such an object supplied as the parameter to a ‘click’ event, but I can’t seem to find any other way programatically to obtain this object in the API documentation.

I’ve looked at the scene graph and node map, however they don’t appear to contain the same object structure as the ‘click’ event.

When I use the objects from either the scene graph or node map with the ‘assignMaterial’ method, it results in an error.