my way of lip syncing is sooooooooooo dodgy but it dose at least give the impression that someone is speaking.
I create the charectors head and draw on their mouth. Then I create another layer that I title 'mouth' then where the charectors mouth is I draw another part of the mouth. And when ever the scipt tells the charector to speak I move the mouth layer up and down so it looks like the charector is speaking.
I never got the hung of the sugested way of lip syncing so I just invented my own way.
Hey, nothing could be easier than lipsyncing with Moho. Create four or five mouthes instead of two, place them in a switch layer and choose a speak for source an you have it. Your way probably works, too, but don't give up on the moho way if you really want to try.
Another solution could be to always cover the mouth when the character speaks, or don't show the head on-screen. I know this is a lame trick, but sometimes it works.