Is this the question you are trying to ask: How do I convert user input to another language?
Google and altavista use machine translation to convert from one language to another. The trick is machine language is good, but not great. But it also depends on how accurate you need your translations (for the most accurate, you need a native of the language to translate to to do the translating).
Otherwise, you'd need to invest in some machine translating software. Or fiddle with some code to interact with google/altavista, but I would think they have policies against people doing that. But I'm not a lawyer...