Ok I made some minimal progress. I think I got the skeleton and animations covered. I got everything in place. I start bi.exe with the -mod switch.

But then it raises following exception :
Script Error in data/export_descr_unit.txt, at line 7028, column 24
Stat_pr statistic refers to non existant projectile type 'crossbow'.
I don't know ...... hardcoded ....... did I forget something?

Oh gods of modding have mercy!! Lol, ok enough for now I'm going to bed.