It would, but you'll need another junction box otherwise you won't have a port for the cable running to the rest of the system. A 5 port might be a neater solution, otherwise you'll need an extra junction B box to connect the shifters.
Ah yeah good point! I guess a Y connector between one bar end and the climbing shifter would do that job as well, means a lot of internal wiring planning though. Cheers both.
So therefore the above should work with a 3 port?