This is my first KDM-theme ever so it might be a little buggy. But at least it works fine on my computer in 1024x768 resolution. It should also work on other resolutions.
You need to unzip the archive into KDIR$/share/apps/kdm/themes/ and modify $KDEDIR/share/config/kdm/kdmrc to read like: Theme=/usr/kde/3.4/share/apps/kdm/themes/SimpleK
The code is based on KDM theme "circles".