The right way to do this is to get the controller to handle UISegmentedControladding controller views as subviews.
[self.view addSubview:controller.view]
It is your responsibility to send viewWillAppear:, etc.
EDIT: The offset you are talking about can be adjusted with:
controller.view.frame = CGRectMake(x, y, width, height);
EDIT 2: In response to tc. comment:
From the documentation UISplitViewController:
Forwarding messages to child view controllers
. . , , . , , . , , viewWillAppear: viewDidAppear: , . , popover, , .
, , . , .