You can run a test build of OpenELEC running Kodi15 on your pi using these steps...
- Ensure you have a working OpenELEC build on your Pi already
- Navigate here and download the latest build for you Pi (1 or 2)
- Copy the downloaded .tar file to your Update folder on your Pi (You should be able to get to it with \\Pi IP Address\ )
- Reboot Pi
You should find it will update and reboot a few times, once it does, you should be running the latest Kodi 15 Test build.