I don't understand. You are Dutch so I assume how to pronounce the name of Haarlem, "capital of the province of North Holland." I have just listened to the pronunciation as given in the Wikipedia article, http://en.wikipedia.org/wiki/Haarlem and I would simply use the Dutch pronunciation. If speaking to someone from the United States, you might emphasize the double "a," and the "e" vowel sound in "-lem," to make it sound as "foreign" as possible, and as possible from "Harlem." Many people in the United States are a) familiar with the name "Harlem" as a low-income neighborhood in New York CIty, and b) unfamiliar with the city of Haarlem. "Harlem" is pronounced with a schwa at the end, "Harl'm." Harlem was, of course, named after Haarlem. If you get a puzzled look when you say "Haarlem," then you may need to say something like "the city in The Netherlands, not Harl'm in New York."

The previous answer was far too complicated. /ˈhɑr ləm/ Stress is on the first syllable and the second syllable is unstressed.