Yes, it's very much the same as sweating copper pipes. One thing I do differently is I try to minimize the number of places where I feed in braze,and try to do it in places where any resulting slobber will be removed. For a head lug this means feeding as much as possible from the top, where the excess tube will be trimmed when the head tube is faced and milled. For this to work, you need to have the entire joint well heated before you start feeding in braze. I push some in, then use the heat of the torch to pull it to where I want it to go. You can actually see where the braze is under the lug as that area will be slightly cooler and darker than areas with void space beneath the lug. It is often possible to fill the entire joint with only one or two insertion sites on the lug. The resulting joint needs minimal cleanup after the flux is removed.