[whpalmer4]

Finally had a chance to get back to this. I downloaded the file, unzipped it, and was able to choose icons out of the resulting folder by the means I described. Not sure why you are trying to select multiple icons or the folder — a given perspective only gets a single icon. I was able to drill down into the folder by clicking the little triangle in the icon well in the Perspectives window, then manipulating the file chooser widget in the usual way.

If you're attempting to extend the list of icons offered up in the icon chooser, it appears you can do so by adding files to the Contents:Resources:PerspectiveImages folder in the application. That probably isn't something Omni supports.