Sorghum syrup and dried yeast are the best place to start. Sorghum has its own unique taste, so your first batch will give you a feel for what it's going to taste like. I kept mine nice and simple so I could easily figure out what the sorghum was contributing for flavors. I think I did 6# of sorghum syrup (same idea as LME), half an ounce of cascade for 60 minutes, then a half ounce of cascade for 5. I primed with spiced cider in an attempt to fight the sorghum bitterness. I hate the taste of the beer unless I pour the yeast into the glass or just drink straight from the bottle. I used safale s-04 yeast.
There are a few different commercial gluten free beers, I've only tried RedBridge, though. See if you can find one in your area and try it out so you have a bit of an idea what the sorghum's going to taste like.