Its hard to milk a cat for sure particularly when greedy bigger kittens are helping. I've done it using a shot glass as a 'bucket' but its not quick unless mom is really full of milk. You could try giving her some goats milk to make her milk come in heavier
www.meyenberg.com could help you find a place to buy it fresh or try a can. I hand raise babies on that usually instead of formula along with a daily dose of liquid vitamins.
It can take a bit to get enough milk out of mom but it can help the kitten.
Cold kittens will be rejected by mom and can't eat well so warming the kitten can help with vigor.
Read here to see about hand raising and how much formula each weight kitten would need so you can figure out how much the little one needs per feeding
http://www.kittenrescue.org/handbook.htm
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