People being able to log to your server depends ONLY in the logonserver.conf where you put which client versions are able to join. There is no DATA for expansion 2.2 yet, having the PTR client can grant you the maps and DBC files (haven't tested them though) and you can raise the level cap manually to 80 BUT no skills/quests/talents for 70-80 and no NPCs/instances in the new area (that island at the top-middle of the map).
You can of course add any custom material you wish but it won't be anything similar to the official release of 2.2 .
Ascent has made some minor core updates (mostly regarding already existing skills) to match with 2.2 features but no DB yet has 2.2 Data.