You are one fortunate dude! Halibut is one of my favorite fish. First, recognize that it is a very white tender fish. Smoke it lightly .... I like Peach wood. Then serve it with a fruit relish .... something like mango or pinapple. Absolutely fine!
The time will vary with the thickness of the fish. But just guessing .... for a 3/4 to 1 inch piece smoked at around 180 - 200* probably around 30 to 40 minutes until the meat is nice and flakey. But be careful, it's easy to over cook fish. Good Luck!