Depends on what equipment you have at home. I use a simple cheap HVLP spray gun to apply it after everything is blasted with silicon carbide. You do need to wear a forced air respirator since it is fairly toxic. You need a paint booth to exaust the overspray, and it smells terrible. I cure small parts in a toaster oven dedicated to the task, and barreled actions get cured using one burner of my bluing setup, with the tank turned upside down to make a cover. It's crude but works well. I am saving up for a proper oven for that, but they are several thousand dollars so I don't have one yet.
So, the answer is, it is not hard to do if you have the proper equipment. Nearly impossible to do if you don't.