I do not think it gets wired to the blower simply because if you just
turn your fan on at the thermostat, the humidifier will constantly be
on.
On my furnace, the humidifier kicks on only when the heat is on, but
once the heat has been satisfied and the gas burner kicks off, the
humidifier also goes off, even if the fan stays on. I do not think the
humidifier will do it's job correctly if just the fan is on and no heat
passing through it.
On my Trane XR 80 furnace, the humidifier is hooked up to the C and Y
terminals on the board. This is not to say you furnace is similiar,
but just to give you a reference.
What does the instructions say that came with the humidifier when you
purchased it?