Wire Remote Starter

[Ikera]

HI,

I'm installing a 2-Way alarm with remote starter (1990 240sx KA24E)

I'm been looking at FSM for hours trying to find a best place to tap into;

-Tach
-Neutral Switch (ground)
-Open Door Switch (ground)

don't want to tap into 3 different harnesses to get these wires or having wires running all the way across from driver side to passenger side ECU if I there is a better place.

Has anyone got good experience installing this things? any advice?

I will also need to wire few other things but I think I got that figures out
-door lock (driver side door harness)
-door unlock (driver side door harness)
-brake pedal (brake pedal lol)
-parking lights (steering column light switch)