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

 import XMonad.Actions.Warp

then add appropriate keybindings to warp the pointer; for example:

 , ((modMask x,   xK_z     ), warpToWindow (1%2) (1%2)) -- @@ Move pointer to currently focused window

-- mod-ctrl-{w,e,r} @@ Move mouse pointer to screen 1, 2, or 3

   [((modMask x .|. controlMask, key), warpToScreen sc (1%2) (1%2))
       | (key, sc) <- zip [xK_w, xK_e, xK_r] [0..]]

Note that warping to a particular screen may change the focus.

warpToScreen and warpToWindow can be used in a variety of ways. Suppose you wanted to emulate Ratpoison's 'banish' command, which moves the mouse pointer to a corner; you could define:

 banish :: X ()
 banish = warpToWindow 1 1 -- lower left