Then I'm really confused about how to hook a TCP Port for decoding if
it's not done via Dissector? I know that's how the development guide
suggested & several of TCP based dissectors worked when we wrote our
internal dissectors. Our dissectors show up in the list of enabled
Protocols. Has Wireshark core functionality changed?
No, not really.
Did you recompile them against 0.99.7? (This is necessary even for