ATL ActiveX and Scroll

hi there
i build an atl activex control and i realy need to implement horizontal scroll capabilities. the window my activex that i want to scroll is derived from CTreeCtrl and i use the vertical scroll of that control but, because i alterate the design of the tree i can't use the horizontal scrool bar of the tree and i need to put another one on the parent window of the tree (the main window of the activex)
i need some advices on that theme
can anyone help me?
thanks in advance