Hey, Sorry to respond so late to this, but I've been out of town. I am the PRO at keeping this simple! My step sister has 12 kids, all slept htru the night by 3 months, and I learned from her and have had no problem with my two.
At six weeks, it's too soon for him to make it through the night, but you can break the habit of nursing to sleep. The best way is to use the sleep, eat, wake pattern all day. As in, feed him as soon as he wakes up from naps, then let him play until he doses, and don't feed him back to sleep. Feed him again as soon as he wakes up, and let him dose without eating. Repeat. At night, nurse him before bed, but then "finish nursing" and then put him to bed afterwords.
Falling asleep once in a while while nursing is OK, but make sure he can fall asleep sometimes after you have stopped nursing.
As the weeks go by, the more he eats during the day, all day long, the better he'll sleep at night. Babies may not seem hungry in the day time, but can often eat more. If they don't eat enough, they wake up during the night. Just a big feeding before bed is not enough, it has to be maximum feeding all day long. Stuff him all day, put him through his cozy bed routine and walk away.
Anything you do for him at night to "sooth him to sleep" will become a dependency. A little crying at first is OK while he learns to put himself to sleep. But right now he's too young, and too hungry to worry about letting him cry. Just get him used to sleeping without eating all day, and wait a little longer. Good luck!