Okay we figured it out. We just had to override the appropriate templates. So for examle if you want to use a css class for your icons on your related items you need to override the relatedTemplate simplate in your ApplicationModule.js with something like this:
//Some customizations require extending the view class.
//Exted the RelatedItem Template to allow for designation of icon by class
relatedTemplate: new Simplate([
in our case we used if and else if so that if iconClass property was defined and we've inherited the icon property the iconClass wins and we don't get two icons by accident.
The great thing about this is that we now can define all our icons via css and their location will be relative the css file not to the html we happen to be using.
Here's the example from our custom.css file:
And the final result