I have a few ideas... put him in the crib after he's already asleep and as he gets used to sleeping there, put him in there when he's REALLY sleepy and nodding off (maybe after skipping a nap or getting a later nap than usual).
Another suggestion I have is honestly have him cry longer than the 5 minutes you give him, if he still chooses to cry when he's super tired. The thing is that you should not worry about the crying, because you already know WHY he's crying. It's when a baby cries without knowing the cause of crying that you should worry about. He's 9 months, so that's his only way of "protesting".
It's also important to keep a routine when you put him to sleep. It doesn't not have to be long and drawn out, but just to give him little signals that bedtime is approaching. We have a small routine we do, and it's really funny because my 18 month old may not have seemed sleepy beforehand, but she immediately starts acting extra sleepy as soon as we start getting her ready for bed because she's so used to going in her crib right after:)
Going to sleep on one's own (when that is the goal of the parents), get's increasingly important (and harder to start doing) as a baby gets older. Start now. I'm not against co-sleeping when that is okay with the parents. I have friends that are completely ok with their kids being in bed with them, and that's their preference...
Another option: Let him know that you are there for him if you'd like by starting off this change by being in the room or right next to him when he starts sleeping in his crib. He'll probably cry, but he'll know he isn't being "abandoned". Move further away from the crib each night until you are out the door, and he's on his own.
I'll mention again- crying WILL happen. It was SOOOO hard for me to deal with my first one crying (I have four) for that long, too. Now, it's a piece of cake, and my babies hardly EVER cry- they are VERY content.