You can use this module with the following in your ~/.xmonad/xmonad.hs:

 import XMonad.Actions.MouseGestures
 import qualified XMonad.StackSet as W

then add an appropriate mouse binding:

     , ((modMask x .|. shiftMask, button3), mouseGesture gestures)

where gestures is a Map from gestures to actions on windows, for example:

     gestures = M.fromList
         [ ([], focus)
         , ([U], \w -> focus w >> windows W.swapUp)
         , ([D], \w -> focus w >> windows W.swapDown)
         , ([R, D], \_ -> sendMessage NextLayout)
         ]

This is just an example, of course; you can use any mouse button and gesture definitions you want.

For detailed instructions on editing your mouse bindings, see XMonad.Doc.Extending#Editing_mouse_bindings.