You don't need bluetile for GridSelect, it just isn't included in the
released version of xmonad(i.e. it didn't exist at that time). My
suggestion is to remove bluetile(it might be possible to have both
installed, since bluetile seems to be hidden though) and install the
darcs version of xmonad and xmonad-contrib, which contains
GridSelect. You can then use it just like any other module.  See the
"From darcs" section here: http://xmonad.org/download.html