Dave,
You can toggle the icons attribute in the flow of the document (assuming the attribute hasn't been locked by an assignment in the API).
= Document Title
:icons!:
NOTE: No icon will be used here.
:icons:
See my cool icon:flag[] icon.
:icons!:
NOTE: No icon will be used here either.
Another solution is to make your own inline macro which operates independently of the icons attribute.
Yet another solution is to use font-based icons, then modify the CSS to control how the icons are displayed (since font-based icons are really CSS-based icons since it's up to the CSS to decide how to handle them).
-Dan