Aw, Jessica. I remember Natty's sleeping turned topsy-turvy around 4 months too.
Ok, you are right, there are lots of different sleep theories out there. In this thread you'll find people subscribe to comforted sleeping where you'll get loads of support if you want to continue to cuddle Peter to sleep, or use the pram or wear him - however you'd like to get him to sleep without crying.
Then there are other methods, like your patting etc (which I started to do with Natty at around 3.5 months as she would get terribly upset in my arms and so it was easier and quicker to settle her in the cot). If you'd like to keep trying with this one (and it sounds like that's what you'd like to do, judging from what you were saying in your post) then the big thing is to try to be consistent with him. If you'd like to settle him in the cot it may well take a few days for him to get the hang of it. They may well be the longest three days of your life! But if you are consistent and as calm as you can be it will happen for you both. I used to get Natty to have her morning and afternoon sleeps in her cot, then her late afternoon sleep would be in the pram while we went for a walk. This worked really well for us for some time.
I'm sorry, I don't think I've been much help, but it is really up to you as to how you want to settle your bubs. Please don't let any books etc tell you that you must do things their way if you want a 'good' baby who sleeps all the time. They are all a load of crap. Best thing is to follow your instincts and stick with a routine and/or technique that works for you and Peter. GL with it, matey.