With engine edits, most of what's being added is the possibility to do these things through mods; the mechanics of training soldier stats besides Psi Skill at a base facility are in OXCE, but are not used until a mod defines a facility that uses them. Examples of mods that do this are Piratez and X-Com Files, since they both run on the OXCE+ engine. In order to use this feature in the base game, you need to write a small mod that tells the engine you want a facility to train your soldiers.