The procedure is simple enough. If you are chatting in hindi and you type 'haal kaisa hai janab ka?' the firstname.lastname@example.org bot will produce in Hindi as 'हाल कैसा है जनाब का?'. At present there are five transliteration bots - Hindi (en2hi.translit), Kannada (en2kn.translit), Malayalam (en2ml.translit), Tamil (en2ta.translit) and Telugu (en2te.translit), and remember that their names end with '@bot.talk.google.com'.
Here is the simple three steps to chat in your native language:
1) First add the bot that you want to your friend's list. (For example, add email@example.com for Hindi). You just need to do this once.
2) Start a chat session with your friend
3) Convert the chat session to a group chat and invite the bot to it.