Its good that you want to learn it, but dont just learn it because you want to converse with people on Lewis, the Island folk are a breed apart, I went with my mate from Glasgow and he was like "Hey everyones English here!!, wheres the damn Scots??" Nope thats how they speak man theyre island folk!

like Steve says your unlikely to get the time of day never mind converse with them, dont take it personally its just how they are quite insular.
Its a bit like the Japanese not wanting you to bow to them, they like to shake westerners hands not bow.

Good luck