Just a quick guide on how I set mine up. Basic stuff, but might save someone a google. Here's the basics under OSX - I believe it's different in Windows, and YMMV, but this is what worked for me.
First, go over to the Reaper WIKI and download the Keymap and scene file.
Scene file at Cockos
Copy of it hosted here at MG.
Then go into Korg Kontrol Editor and open the scene file.
Once that's done, in Reaper:
Preferences > Audio > MIDI Devices - Enable the controller. In Windows I think this may show up as the actual name of the device, but for whatever reason mine shows up as "SLIDER/KNOB".
To rename it (if you give a shit) right click it, Configure, and give it an alias.
Once that's done, note that tt will be disabled by default, so right click on it and enable it w/control:
Then head on over to Preferences > General > Keyboard.
Click "Assign keyboard shortcuts to actions or change existing shortcuts" which brings up this window here. Then click Import/export.
Import the keymap in the zip file from the wiki/patch library. That's it! Push buttons, record stuff, forge metal!
you know in logic, I just plug in the usb and it works...
But that is some serious effort of a thread!