T-rex is the triscene.
Its very easy to do that now with Jenny's xcom editor , its on strategycore in the files section for TFTD , called "Xcom Editor".
It has the blue background and lots of colors and imported graphics from the games.
To increase damage to a unit, you would increase the resistance value. 100 is normal (no damage adjustment at all). Somewhere on the ufopaedia is an explanation of how the resistances formula is used, IIRC it is calculated before taking into account armor reduction.
Here is a small example : http://www.ufopaedia...hp?title=Damage
(search for sonic cannon, under lobsterman soldier)
In the editor you would be modifying Gauss, but it is with the same method. I suggest backing up your exe (and rename later to have the editor read it - swap) .. so you can compare to normal settings at times between adjustments, for reference.
To have a unit take more than normal damage, the resistance would be over 100 .
It takes less damage than normal if it's below 100. The asterisk in the editor reminds that Unarmored 'also effects aquatoids, civilians and zombies' (in addition to xcom troops with only coveralls/diving suit)
Damage modifiers for TFTD table on ufopaedia.org : http://www.ufopaedia...odifiers_(TFTD)