Here is a link to a page that you can download the manual from.
scratchlive.net
Plug the direct outs of the cdj channel one and two into the inputs of the SL-1. Use the line 1 and line 2 outputs from the box into line inputs on your mixer. Make sure the channel on the mixer is switched to line. IN the Scratchlive software go into the set-up / hardware screen and select "line" as your audio input level.
That should do the trick.