Download Reaper for linux from http://landoleet.org and make sure you have JACK installed.
git clone http://www-dev.cockos.com/wdl/WDL.git
git clone https://github.com/reaper-oss/sws.git
cd sws
git checkout next
Run the action "Write C++ API functions header" to generate git/sws/reaper_plugin_functions.h
from the action")
make
ln -s `pwd`/reaper_sws64.so .../REAPER/Plugins