Highest OTL Moslem %ages in New World countries:
Guyana 6.8%
Suriname 13.8%
Trinidad and Tobago 5%
Which means that any PoD has lot of work to do.
Actually, the most plausible mechanism I can think of would be an influx East Indian Moslems to one of the very small island "countries", which requires much smaller numbers. However, AFAIK all those colonies had overwhelming numbers of blacks. And AFAIK, very few Moslem blacks were exported as slaves from Africa. Most came from the coast, which was pagan. Also, where Moslems were dominant, they were the on-shore suppliers and sold non-Moslems by preference. (I'm thinking Senegal and Gambia, which today are 95% Moslem.)
So two possibilities:
Some small colony happens to import most of its slaves from Senegal and Gambia, at a time when the dominant Moslem tribe there wants to get rid of a rival Moslem tribe.
Some small colony has a particularly ugly slave rebellion, leading to the death or expulsion of most of the black slaves and their replacement with Moslem indentured servants from South Asia or the East Indies. Then perhaps a lot of the remaining blacks convert to Islam, to escape the repression applied to them.