I don't think he's saying that putting his sensors in the spare wheel stops the light from coming on. I'm reading it as he's blocked the light and the sensors are basically stored there.
EDIT: I was wrong, apparently the DIY linked calls for drilling into the spare rim and installing all 4 sensors there. Somehow this works and reads the spare pressure correctly, tricking the TPMS into thinking there are 4 identically inflated tires on the car?
OP's link no work: (
http://www.quebecfrs.com/forums/guid...teme-des-tpms/)
That said, I've personally never had my TPMS light come on. I've got sensors in my summers and stocks (winter) and I've had the pressure drop as low as 21 psi in one tire with no light. I habitually check with a gauge anyway so I don't care but it seems odd.