I don't believe that there is any style bit or function you can call to turn a normal toolbar into a floating/docking toolbar.
I stepped into some of the MFC code for the CFrameWnd and CToolBar. It seems that there is quite a bit of additional coding going on to support this behavior.
This is appears to be one of those times where MFC is not just a thin layer over some WIN32 functionality.
If this is not the case I, too, would like to hear how!
HTH,
-mordell