How to set ScummVM to open a game that GOG doesn't usually use ScummVM for?

[LoneFenris]

I'm trying to figure out how to get The Longest Journey from GOG to use ScummVM instead of the usual Wine as it runs much better in ScummVM than Wine.

I've read https://github.com/Heroic-Games-Launcher/HeroicGamesLauncher/wiki/How-To:-DOSBOX-and-SCUMMVM but that seems to handle the case where GOG's distribution is already trying to use a packaged ScummVM rather than the system one. For Longest Journey, GOG's distribution doesn't try to use ScummVM at all.

As a workaround I tried creating a separate launcher in Heroic for it by Add a Game, selecting Linux and using the executable line flatpak-spawn --host flatpak run org.scummvm.ScummVM tlj-win but that also seems to fail as it expect the executable to be a file.

Is there a way I can manually set the game entry to launch in ScummVM instead of Wine?