You can try to use the Slackbuild for 13.1 from slackbuilds.org, ( http://slackbuilds.org/result/?search=i3&sv=13.1
). I've had a bit of luck with them.
If you don't want to go through the hassle of compiling the dependencies, you could try a few of the more simpler tiling window managers, such as Echinus (My slackbuild is located here
at linuxquestions. See the last message for the newest version compiled and running on 13.37), dwm
, or any of the others.
Echinus has a simple, easy to read configuration file, dwm is configured completely from the source code and has to be recompiled each time there's a change, but it's rather easy to do and learn. Unfortunately I haven't had much luck with many of the others, such as subtle, ratpoison, ion, i3, and a few others I don't remember, so really can't say anything about them.