Yes, there's a way to do this in your case - but it requires that you input a destination airport that is no more than 90 miles from each of your desired endpoints. So in your case, tell it that you want a round trip to SNA, and select "90 miles" from the "airports within" dropdown.

Now, there's no way that I know of to do this with airports farther apart - although I'd love for someone else to chime in and prove me wrong.