You can do a
type >debug: blah
in a shell to verify debug catching works OK for you - it will show up in logtool.

If the log is empty when you connect the receiver, it means the xbox controller class was not loaded by Poseidon. Are you sure it shows up in USB Settings' Classes list? If it does but there's nothing in the log, go to USB - >Devices, find the xbox receiver, doubleclick it and make a screenshot of the window that'll open after the dblclick.