I found the layout of the ecu, as you can see in the picture below there 4 connectors, you'll need the one with 32 connections.
The one were the measering pins are connected in the picture.
The white/red wire connects to no.30 (econo), and has or 0 volts or 12volt.
There are also other ways to connect a lean-burn indicator light, in the HX and for sure the d15z6 the engine usses a narrow-band lambda, if its in lean-burn it signal dissepears becouse its out of its measering range.
It's calculating its AFR with a rpm-fluctiation sensor.
The older d15z1 vx had a wideband-lambda, but when it brakes down it's very expensive to replace so the honda engineers thought away around it with the RPM-fluctuation sensor!