And i thought this was about using the 'impossible tech' workaround, wrong.
What you really want is TA's tree features and its structural approach, right?
Sic, i too needed some sort of control over a few areas of the 'standard' research_grid (For DA purposes, that is) to insert some Apocalypse concepts straight in between Discovery_Sphere & Techno_Victory... and soon, realized the slots only required tags & preqs to be usable.
Trick was to balance it all out. Lotsa testing yet to do, but i'm slowly getting fair enough results.
If only i had access to the TA editing tools when i planned these alterations, it coulda been a LOT easier.
Bof, it's real fun to fiddle with these issues anyway; in X-Worlds players will get... 4 new Capital buildings, about 40+ new technos, plenty of extra Trade-Goods, a whole bunch of X-Com specific weaponry pathways, possibly three all new pseudo-indirect Victory conditions, etc, etc.