AE Button Plus may not be free, but it will function with almost 100% functionality without registration. Technically though, you are only supposed to use it for 14 days if you don't plan on registering even though it will continue to work. For $7 you get a few added features, but those are not needed for what I mentioned above.
I registered the app to support the developers, but its not required to retain functionality.
AE Button Plus works beautifully with Mortscripts as well, which I have done on my 700wx and now on my 6800.
Here are some pics of what it looks like when AE Button Plus is switching. You can disable the notification popups as well if you like.
