Technically, your wife must apply, you can't apply for her. She must sign the form, and you must include whatever original identity documents are required (passport, etc.) (they will be returned to you). (In some cases, a certified copy provided by the government agency that issued the original document will also be acceptable.)
Because you need to attach the application to your tax return and mail everything in, you will need to obtain original signatures and documents from your spouse somehow, either when you next visit your home country, or via International express mail of some kind.
