First off: this is based fully on the concepts documented in the main library, but with a few things different:

Every packet must be have alexiil.mc.lib.net.impl.McNetworkStack.ROOT as it's root parent network ID - otherwise it will crash when you try to send it All network connections are buffered until the end of every tick - so you cannot expect them to arrive before normal minecraft packets, unless you explicitly call alexiil.mc.lib.net.NetIdBase.notBuffered() on the network ID.