Thanks for your reply Joe and Brandon.
I would suggest parsing the selection and wrapping the pieces in span tags as needed.
So, if you had content that looked like this:
<p>First paragraph</p>
<p>Second paragraph</p>
And you selected like this:
<p>First paragraph</p>
<p>Second paragraph</p>
The result would be this:
<p>First para<span class="Highlighted">graph</span></p>
<p><span class="Highlighted">Second pa</span>ragraph</p>
This is what WLW is currently doing when I select text and click the B I or U buttons on the toolbar.
I've suggested the dynamic template plugin, but many of my clients are looking for something that end users can use without requiring a plugin.
Thanks for the great product and for considering this request!
Don
Don Worthley