Hyperion,
Let me try explain what I meant again (last time was about 02:30AM lol)

In your FSUIPC go to "Joysticks",click on the right arrow till you get to "3 of 7:Seperate Throttles Per Engine".You'll see "Reverse","Idle" and "Max" with "Set" under each one.Move your throttle all the way back and click on "Set" under "Reverse".Move it forward,about a third of the way open,and click "Set" under "Idle".Then move it to the full open position und click "Set" under "Max".Then just say "OK".You should then have reverse thrust.