where exactly is the negative of ignition coil on sw20

[2fas4u]

hi in relation to hooking up a monster tacho to a 90'SW20 MR2, where exactly is the negative terminal on the ignition coil. could someone please enlighten me with a diagram or pic so i know what to look for when i open up my engine bay cover. alternative is to just use the factory rev meter and get one of those gizmo shift light but how would that hook up? wat wires do i look for? cheers.

[TWSTD]

use the ign output from the ECU - i also have a gizzmo light on my 3sgte (not in SW20 though).