i don't know the colour codes, but there should be 3 lines into the BCS (boost control solenoid) which you say you've already found (bolted to the side of the air box.)
remove all 3 from the BCS,
- the one from the intake side of the turbo (pressure line) goes to the inlet of the MBC.
- the one to the actuator goes to the outlet side of the MBC
- & the final one which should go back to the air intake pipe you block up.
you still have to leave the BCS wired up or the ECU won't be happy, just leave it in place with no pipes connected to it