Analog tachometer and 704 control question

[Conter4x4]

Just got a new analog tac to go on my boat. I have a f90ja Yamaha with a 704 single binnacle control I was wondering if anyone has a diagram of how to wire the tach in and what pol I should set it on

[fairdeal]

coming from the keyswitch are red, yellow, black and green wires
red is always on power
yellow is "ignition"
black ground
and the green is tach signal

The F90 is a 12 pole alternator
(or if the tach settings are in "pulses", is 6 pulse)

[boscoe99]