Is there way to convert just some service methods in a WCF to webMethods? Or add webmethods to an existing WCF?

Question

I have an existing WCF, which already has service methods available on it. I would like add some webMethods to this very same WCF to be accessed via a web browser.

Is this possible?

I see plenty of examples online on how to setup webMethods, the uriTemplate, etc, but nothing that clearly shows how to accomplish my above question.