Easy & quick.
Clean jars, fill with milk to a 1" headspace. Wipe rims dry (but not with vinegar, a tiny bit will start to clabber the milk) and put on lids & rings. Load the canner like usual. Vent for 10 minutes then close it up. Bring to the correct pressure for your altitude (10 pounds for me) and as soon as you're there turn off the heat. Leave the canner on the burner. When the pressure is zero, open her up and there you are. The milk is then shelf stable, refrigerate after opening like normal. I found a jar that was 14 months old and it tasted like just canned.
You start with everything room temp. The milk can be room temp or just outa the fridge. Washing the emptied jars in cool/cold water helps keep the calcium from setting onto the glass so much. But it's pretty tough to actually get the jars what most consider 'clean' no matter what you do, short of scrubbing with a Brillo. I can't get my hand inside a jar to do that. They're clean, just a bit cloudy. So I just keep a set of jars for milk only and motor on from there.
The milk will change color just a little along with the taste will get just a bit creamier. Now my experience is only with whole store bought milk but plenty of others have done this with any kind of milk. America is one of the very few places that you usually buy milk refrigerated. Many countries it is canned in one way or another and just sits on a shelf.
I add 2 tbs of sugar & 2 tps of vanilla to each quart because I like it that way. Some of the easiest canning you'll ever do.
Cat