The preferred way is with the BLM port on a quad IIC module. This combines MIDI in, MIDI out and power connections on a DIN8 socket. There's a matching DIN8 on the BLM case; I've wired up a DIL10 header to go to the miniCore board.
You can also use a DIN MIDI port on the SEQ, just connect and define which one you use. This is how I've tested mine because I can't easily get a hold of the PCB mount DIN8 to complete the quad IIC.