Thanks for the reply Pete.
Regarding your first point; past the indent it is not just a button press, as when I go to the saitek calibration software there is an incremental change in throttle value below the indent (which is indicated by the red area reducing). Also this is backed up by the fact in flight simulator, that you can still be applying slight throttle below the indent, or close the throttle when you pull it right back.
According to this thread http://www.flightsimworld.com/forums/in18600&st=0 and the post dated Jun 18 2007, 03:41 AM, it is possible to calibrate reverse thruster on the throttle axis.
I will try your ways though- it may be the only way for me to get it to work. Thanks once again!