CLEP Spanish: Best way to learn for someone with ZERO prior knowledge

[Ideas]

I would say it could be done, but only if the person was gifted in languages like you said (and somehow didn't know this yet), already knew a related language very well, or had an excellent tutor or tutors for hours a day. But it would still be a difficult full-time endeavor. Most likely they would have to give up speaking English during this time, like others said.

They would probably also need to be a good test taker in general and good at reading comprehension (in English). I know that my general (non-language) test-taking skills helped with some Modern States practice questions.