Okay I don't think you understand my point. Let me reiterate through everything so we think about the same thing.
You have a server sending a SPlaySoundPacket to the client. This packet contains info about position of a sound, volume, pitch.
Client's network manager captures that packet and calls it's readPacketData and processPacket method. I need to hook my code up to that "processPacket", that means I need my code to run whenever that method is called. Intuitively I'd subscribe to an event that is called on packet reception, check what packet it is, if it's that sound packet I do my stuff, otherwise I just return. That's what I want to do, and the end goal is not relevant here. I've described the entire process for you.