Okay, first off, you will need to QT him for a good two weeks. That's your first step. :) Make sure that no-one touches anyone else, including water splashes, cleaning supplies, décor, etc.
Beyond that, just his basic acclimation is like normal. (And this guy will most likely be far healthier than your pet store fish and better able to handle stress and anything else.) :)
Float him in a cup in whatever bowl or QT container he's going into for about an hour, putting in small quantities of water every 15 minutes so he can get used to the new chemistry and the new temps. And turn the room/aquarium lights out, this will make him feel more comfortable. I'd leave him in the dark for a good 24 hours, just so that he can adjust and rest. I acclimate all of mine in my bathroom (easy access to water, nice long cabinet with two sinks, and a closet that's dark where he can go while he's chilling out).
I just offer then a pellet, maybe two, when they're in their cup. I don't want to give them much because of their stress levels, and also because they rarely eat it. It's easy to clean any uneaten pellets out of the cup before he goes into his QT container and keeps everything cleaner.
I don't change the water in the QT container for the next two or three days. To combat high ammonia during that period, I put in a couple of drops of prime every day. This way his water is really clean for him without having to stress out over water changes.
I put the QT container *full* of plants so he has lots of places to hide and feel safe. :) I have a plastic bag full of silk plants from walmart, and I pull the blooms and leaves off of them. They don't have any metal, they're soft, and some of the flatter ones will float. These are my QT plants. I wash them/boil them afterwards so they're clean for the next one, but that works great because you can get a lot in there for cheap, and they will fit in any size/shape QT container. :)
Then just feed like normal, normal water changes for the QT size, and let him hang out for a couple of weeks, then he's good to go. :)