I don't know if this is possible or not, but it would be nice if we could highlighting for color, linetypes and spaces on symbols similar to what we have with Xrefs.
Closes thing you can do with symbols is use the min./max. scale to show different color versions at different scales. One of my long time wishes has been GTV like support for symbols where we could select from multiple views of a symbol.
What is the reason for you wanting to have the highlight? Might be another way to do what you are looking for other than symbols?
Thanks! - Josh Do. Or do not. There is no try. Josh's Digital Downloads is come back online soon. Stay tuned. (soon is a relative term)