W.O.
I got the book "The Secrets Of The Babywhisperer" at the library when my dd was a baby and I had the same trouble, it was a great help! It gave me strategies for getting her to sleep without leaving her alone to cry.
I know you didn't want to hear this, but, even Ferber says not to do his method until 6 months ;), So maybe start with some gentle withdrawl techniques, or let him cry while you are in the room soothing him so as not to loose his trust at this tender age, then in one month move onto a method like Ferber's controlled crying. (I could never let my children cry for more than a few minutes without checking on them, one time my ds's leg was caught in the crib bars!)