As the Islander is built in China for Kanilea, the Hawaiian folks should have good enough quality control that it shouldn't' need a customer set up. I've never played an Islander, but I've never heard anything negative.
I think that the lo G string must have a higher tension, making it harder to press down to the fret. I recommend taking it to your dealer, and ask him to measure the string height all across. If the nut isn't filed out to fit the lo G string, it wont' be the correct height. You could try it yourself, the worst you could do is ruin the nut.
Maybe another Islander owner could chime in here???