Yes, it is possible. Modded tech trees overwrite the originals in the sandbox and the campaigns.
All you need to do is place your tech tree in the data\techtrees folder of your mod (should be in Galactic Civilizations II - Ultimate Edition\Mods\The Name of My Mod). Then change the name of the tech tree to match the race you are playing in the campaign (Terran_TechTree.xml for DL and TA, Drengin_TechTree.xml for DA). Afterwards, open the file and change the DisplayName accordingly (either Terran or Drengin). That is all.