This is a bit of a can of worms once opened, but if you are good with low-level TCP/IP communication (binary and hex), it may not be too cumbersome for you. What you'll want to do is review the AMF0 and AMF3 open specification documents from Adobe, but beware that they are a bit dated (there are some "anomalies" in regard to data typing). For the server side, BlazeDS is open source, so you might want to download and decompile the JARs to see how it does it. I'll warn you in advance though, don't be surprised to find some pretty messy code inside if you do decompile Blaze. For the client side, dig into the classes in the mx.messaging package.
Dan Orlando Adobe Community Professional
Author, Flex 4 in Action (Manning Press)