i've noticed that the same gauge will give you "faster" readings if hooked up to the o2 sensor in the engine bay as compared to the wire that runs to the ecu...
this makes absolutely no sense at all to me, but its tried and true...
friends accord had it hooked to ecu incoming o2 wire and it was slow as hell, but then straight to o2 and it responded right as your throttle position changed... very odd...
but you can do it either way, check the pin out for your ecu and just hook it up to the incoming o2 wire... or straight to the o2 in the engine bay for better results...
EDIT: and your name would imply that you LOVE cheap phones or what? vtech?
AND: auto zone.com has a repair section WITH wire diagrams that have ecu pinouts so if you know what ecu you have then you should be all set with that site and the information it has... check repair and then manuals