Why not grab the packages from AUR instead? For instance,
xmonad-contrib-darcs: http://is.gd/3r09GG

AUR xmonad-darcs and xmonad-contrib-darcs both fail on dependencies which is what drove me to switch over to the haskell- repos in the first place. Of course I can edit the pkgbuild or fork that package to yet-another-AUR-package but my xmonad installation is part of a fully automated install process and I'd rather not. If there isn't a good alternative, I'll just edit my xmonad.hs to stop using (the excellent) X.A.2DNavigation until 10.1 is officially in your repos.