What about having an extra stylesheet under /cms/css/ called extraStyles.css or something, and have SS detect that that stylesheet is there, and parse through it, then populate a dropdown field in the cms editor with the styles that are in that stylesheet. This way a site designer could specify specific styles that the user can apply to text, images etc etc.
I think it would be best to wrap a span around the selected text/element and apply the style to that element.
<span class="backLink"></span>
. Just like the Sig master said.