I need a real creative mind for this one. I bought a condo with an old custom build corner shower. I found a neoangle shower that we liked and demo'd the old. There were two concrete beds, one poured level with the subfloor and then one that was shaped with the proper drop, etc. I decided to leave the base concrete intact because of the potential damage that I might have done busting it out. I decided to drill out the drain hole and everything worked perfectly and the shower looks great. One catch though, as you know the 2" shower drains require that the plastic nut be tightened from the back side. Because of the concrete (about 5-6"), I can't get the nut up to the drain which means I can't get any backside pressure to that drain. My initial plan was to puddy and silicone from the shower side and then try to make sure the plumbing had slight downforce. Did not work. I was wondering if it was possible to maybe solvent weld the drain to the PVC and then potenially have the PVC treaded so I could apply pressure to the underside of the concrete. If they made an deep depth shower drain that would do it but don't think this is too common of an occurrence. Any Ideas? Let me know if not clear. Thanks,

1.You have a plastic drain fitting that goes through the bottom of the shower enclosure and is held on by a nut on the underside and on the part that you will eventually be standing on there is a strainer, right. There should be a gasket that goes in between the lip of the drain and the shower base. You can substitute that for putty if you wish. I usually go with the manufacture’s recommendation especially if I have to to keep the warranty valid. Put it all together.
2. You have a proper size abs or PVC pipe coming up through the floor and you have it cleaned and at the right height to accept the drain.
3. Now you dry fit everything so that you know it will work. In other words put everything down but no glue. Looks good? Now take it off, apply the glue to female shower fitting and male pipe end and put it together. Stand back to see that it is how you want it.

See picture here. http://www.plumbinglessons.com/sup/showerdraindraw.jpg