You don't have to worry about changing control over.

The mouse isn't seen as an entity. It doesn't have any behaviour. All that needs done is for it to be switched off as you do.

What you do need to worry about is checking you've used the plbiped script right. Have you given him skill values for example? Other than that just make sure your camera is set and there shouldn't be any problems at all.

Tinker around with the skill values and if your still stuck then get back to us with a screenshot.