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

 import XMonad.Layout.IM
 import Data.Ratio ((%))

Then edit your layoutHook by adding the IM layout:

 myLayouts = IM (1%7) (ClassName "Tkabber") ||| Full ||| etc..
 main = xmonad defaultConfig { layoutHook = myLayouts }

Here 1%7 is the part of the screen which your roster will occupy, ClassName "Tkabber" tells xmonad which window is actually your roster.

Screenshot: http://haskell.org/haskellwiki/Image:Xmonad-layout-im.png

For more detailed instructions on editing the layoutHook see:

XMonad.Doc.Extending#Editing_the_layout_hook

All these items are questionable. Please let me know if you find them useful.

• shrink/expand
• allow roster placement on the right side or even on top/bottom
• use arbitrary layout instead of grid