I read somewhere that LGing can be used in learning foreign languages, but nothing was mentioned about the exact technique in the article.
Sometimes I have dreams about speaking and writing in Greek, though I'm not fluent in that language. I know only scraps, in fact. I haven't practised it for some 10 years maybe, and I'm not sure whether I can say a whole sentence in Greek now. My DG speaks in Greek from time to time too. Last time he was speaking in Turkish, but my Turkish is fluent, so it doesn't apply to this thread.