Hi. Follow these instructions:
- Install LoL in lutris via this install script:
The easiest way is to type in a terminal: lutris league-of-legends-windows
- Do not launch the game at any point during the install. Once the lutris install script finishes, right click LoL in lutris->configure->game options. Change the executable to LeagueClient.exe in your pre-existing install.
You should now be able to run the game. If this doesnt work, copy the Riot Games folder from your pre-existing install to /home/your-user-name/Games/league-of-legends/drive_c/. it is safe to merge/overwrite the existing Riot Games folder that is in there. Next set the executable to the LeagueClient.exe in that folder instead.
I plan to do a video on this at some point soon.