Japanese pronunciation would be Kah-Leen, flat with no emphasis on either syllable. To American ears it would sound like there is emphasis on the first syllable because words with flat intonation barely exist in English. When it comes after a vowel the Japanese R sounds more like an L, but it's kinda in between the two.
I just say it Car-in when speaking English. If I'm speaking Japanese I'll say it the right way. Generally I follow that rule... I never pronounce "karaoke" the Japanese way if I'm speaking English, and so on.