From Geofex:

Ok cool!So,The 2 other lugs are out's.Thanks!
Input goes to the in of the circuit and to one outer lug of the jack.
Center lug of jack goes to output
Other outer lug goes to the Out of the FX board.
And yeah, it will suck tone because it's always sending the signal to a loading circuit, even in bypass. So the bypass signal is pretty crappy.