Since the early 90's all Scotch Whisky corks are cold wax rolled, they're tumbled with blocks of wax to coat the outsides. This was mainly to combat the problem of dust coming from the corks so I wouldn't bother waxing them.
It sounds more like they're getting too dry, one of the problems of central heating/air conditioning is that the humidity is usually quite low and that your temperature is a bit high. I always recommend that bottles are stored in the same type of conditions as wine no matter whether they are sealed or opened.
I'd try keeping them in a household fridge which is normally around the 4 to 6 degree range. The only problem you may encounter would be cold floc but that's not a real problem only a visual one and once you've poured a glass of whisky and left it out for a couple of minutes the floc will disappear.