I think mail is your only way, there is no way to send it through online. Don't forget about international mail rates and rules, i don't know much about that but you may want to look it up.
Viewing post in How can I get this TIN number ? (need help)
by mail they never reply by phone, anyone who claims to be from the IRS might be a scammer unless in rare cases when they do you have to let them know what they want to talk about. Do not give them infomation unless you know the IRS has the same infomation has you. Never give money, ITIN does not require you to buy anything.