When my son was that age, we had some sleep issues, too. Mostly with sleeping through the night, as I'm lucky enough to have kids who will actually voluntarily nap if they're tired. My mom suggested that he may not be sleeping through the night due to hunger, so at night when we went to give him his last bottle (and the one that I fed him while I rocked him to sleep) I gave him a mixture of formula and baby food bananas. I know you said the baby is breast fed, so you'd probably want to do a bottle of breat milk and mix it with the baby food bananas. It makes kind of a smoothie that sits heavily on the belly and helps them sleep.
As far as what you're asking about the 3-day sleep solution, I've never heard of it. And when it comes to following Dr. Baby Guru's advice (and this is anyone who claims to be a baby expert) ....half of them don't even have kids. The answer isn't going to be found in a book or pamphlet. Its going to just be more trial and error. Also, one thing that I've learned in my seven years as a mother is that... A) Yes, sometimes you have to just let them cry it out and B) If you don't take care of yourself, you can't take care of anyone else. See if you can find a friend or relative to take the baby for a few hours so you can take a nap and get yourself rested. Even if you don't nap, and you just do something as simple as take a long shower...just something to help YOU to feel rested. Because otherwise, its going to make this process that much more tedious. When my daughter was born, she didn't sleep through the night, and my son was old enough that he didn't take naps, but couldn't be left by himself...so needless to say, I NEVER SLEPT! I was up all night with my daughter, and up all day with my son. It was hell, so believe me I know what you're going through, being exhausted and feeling unable to take care of yourself, let alone two kids. So....try to get some sleep. Try the banana thing to help your baby get a "fuller" belly when its sleep time...and then, if you know that he's fed, dry, and just tired....let him cry it out. If he's bulking at sleeping in the crib, and everytime he cries, you take him out and give him what he wants, then he learns that crying gets him what he wants. Even though it sounds silly to say about a baby at that age, its still true. Once he's fed, changed, and laid down, just leave him laying down. If you have soft music you can play, play that for him. Those little toys that attach to the crib and play lights and soothing music are great for that. You may even want to lay him in there when its NOT naptime, and let him look at the lights and listen to the music, just to get used to it, so that he finds his crib to be a soothing place, instead of a terrifying place. Does that make sense?
I hope that I've helped in any way, and I wish you the best of luck. Just remember....it can't last forever, and eventually "this too shall pass". lol. Even though right now its probably about the last thing you're ready to hear.