Hi Susan,
Wow, it is sad that we are beginning to put the disclaimer for people to be nice and supportive at the end of our requests...I've had to do it too.
When our baby was getting rice cereal we did it separate from the bottle. We mixed up some of my breast milk with her cereal just to a consistency thicker than the milk, and gradually make it thicker as she was doing okay with it. She absolutely loved it too!
As far as how much, I think they recommend like a teaspoon or maybe half a teaspoon of cereal and then enough milk to make it thicker. Maybe start in the morning, and then increase it to a couple times a day, and increase how much you give him, and move onto thickening it too. I've never done it in the bottle, but I've heard that you need to cut a bigger hole in the nipple so the cereal will go through it. Hope this helps :)
Happy 6 month birthday to your little guy!
Jody