You should be able to copy .kodi/ over to the other install. The best way to do so is as follows:
At the console (see Wiki - OSMC) and run the following command:
sudo systemctl stop mediacenter
tar -czf kodi-backup.tar.gz .kodi```
You will now have a tarball in /home/osmc which you can download to your PC using WinSCP / Cyberduck or another SCP client. After setting up the new Alpha 4 install, run the following commands after transferring your file back to /home/osmc.
```sudo systemctl stop mediacenter
tar -xzf kodi-backup.tar.gz
rm kodi-backup.tar.gz
sudo systemctl start mediacenter```
Everything you should be as it was. Please note that as we don't have network configuration running from Kodi yet, you'll still want to set up any custom network settings in the OSMC installer
Sam