If i'm not mistaken, it would be: "bagaimana nak cakap ... ?" or "bagaimana mengatakan ... ?" (i think this one is formal) I'm not a native speaker of Malay, but i hope it helps :)

you may as well use "apa _____ dalam bahasa melayu?" as the simplest way of asking. Anyway, razi ismail's answer is the informal way of saying it and yeah, i do agree with him about using the 'ek' or 'eh' in your sentences.

"Macam mana nak cakap ...xxx... ek?" 'Ek' is optional. It's not in dictionaries but I'm sure your Malaysian friends will be blown away when they hear it. Hope this helps ^ ^