We force-fed our male, 14, for a few weeks when he had calicivirus in the fall. We were instructed to give him 4 full syringes of AD (undiluted) at a time, twice a day. That is actually not that much out of a can. We got a quick lesson from our vet's technician. We were lucky that Bertie didn't struggle much after the first couple of times.
You should ask your vet how much you need to feed, watered down or straight, and then try to stick to that. Our amount was the daily minimum our 10-lb. guy was supposed to get while he was ill.
My husband knelt on the floor with the cat backed in a corner. He would hold the cat's head up (hand covering the eyes) and tipped back with one hand, which makes the mouth open, and angle the syringe in from the side, as far towards the back of the mouth as possible (but not down the throat). Let the head go so the cat can swallow naturally and get its bearings. Repeat and repeat.
I know there are choking risks from feeding too fast and getting it down the wrong pipe. In our case, nothing like that never happened and I think our cat appreciated getting it over with quickly. He rarely threw up. He never hid at feeding time. They are all supposed to like the taste of AD.
I just looked at a syringe to see how much it holds and it doesn't say, but they are about as wide as a woman's thumb and maybe 3" long. You probably have the same ones. Clipping a bit more off the tip will make the food go in more smoothly. (The syringes can get very stiff and hard to use over time, we found, even though we cleaned them carefully.)
My husband developed a good, fast technique, and I honestly think the cat began to prefer force-feeding to the trouble of chewing, weird as that sounds. Before most feedings, we'd offer him mushy, smelly wet food (a different flavor from AD) in a bowl, and all-meat baby food on a spoon, just in case he'd eat. If he rejected those, my husband force-fed. I'd fill two syringes and race to refill one empty one as he used the other. It was that quick. The food stayed down, Bertie recovered. His first voluntary food was a jar of all-meat chicken baby food, fed from a baby spoon.
Force-feeding can keep a cat alive, or prevent it from becoming more ill, so please try not to view it as being cruel. Yes, it can be uncomfortable, but I think cats adapt to it, especially if you can develop a predictable technique and let them swallow and breathe normally. Instead of feeling bad for the cat, try to think positively about all the good you are doing: delivering nourishment and strength, and keeping the liver functioning. Cats pick up on our feelings and your cat needs to trust that you are being helpful to him.
Good luck! And many vibes: