Locate the file named "dosboxmegarace_single.conf" that is inside the installation folder, open it with notepad and change the word ENG from this line:

RACEPRG ENG ADP220 SBP2225 JOY0000-0000-0000-0000 EMS 386 WRIC:\

With one of these words that matches the language you want:

FRA
GER
ITA
SPA

Then save the file and launch the game.



For example, i wanted spanish subtitles so i modified that line this way:
RACEPRG SPA ADP220 SBP2225 JOY0000-0000-0000-0000 EMS 386 WRIC:\

I hope the GOG staff will add the option to choose the language from the launcher.