Interesting trick! A set of <q></q>s will encase text within a set of double quotes. However, if you use a second set of <q></q>s within that, it will automatically appear as single quotes.
For example:
There are times when you may want a character in a story to addemphasiswithin their dialog.
<q>There are times when you may want a character in a story to add<q>emphasis</q>within their dialog.</q>
Notice the single quotes around the word emphasis which are caused by my not ending the initial <q> until the end of the sentence.