There is actually no way to specifically trigger any other language for the Verified by Visa or MasterCard Secure Code site.
This is because the bank that issues the credit card will control the language of the user's interface.
The merchant does not need to worry about triggering different languages because the bank that issued the credit card will display the authentication window in the language that cardholder prefers, based on settings the cardholder has with that bank.
In order to test this case an actual issued card is required, or the merchant can contact their issuer for testing card numbers (if available).
