Personally I support the idea of making your own hookah setup and I may still try and make my own again some day, the problem is that you HAVE to get it right. Many folks have made watermakers using pressure washers and industrial pumps with great results but if you drink bad water you get the runs. If you do the hookah wrong you die.
How does inhaling rubber kill you? Let me count the ways. Most likely is drowning. Inhale a serious irritant deep into your lungs and YOU WILL COUGH like crazy. You may vomit. Think you can handle the worst coughing and vomiting fit of your life at 30ft of depth? Well, technically you can vomit into a SCUBA regulator and you "could" survive without drowning, but you will only have a chance if you've taken a scuba class. This is the kind of thing they teach.
Are you going to safely swim to the surface while continually exhaling in a controlled manner as they teach you in scuba class to avoid a punctured lung or air embolism? If you bolt for the surface and can't control your breathing you get a punctured lung, air embolism or both.
So you make it to the surface. Great, now you have aspiration pneumonia, and if the particle is deep enough and stay there, you have pneumonitis. As long as you have access to steroids, antibiotics, diuretics (for the pulmonary edema) and a ventilator you'll be fine.
Some oil left over in the compressor or on the o-ring you used? See paragraph above. The inside of the lungs are coated with surfactant (soap). They really don't like oil. It takes a lot less inhaled oil to ruin your lugs than it does to ruin paint.
Now that I've said all that, I have breathed from an industrial compressor, through an industrial hose attached to a SCUBA regulator and lived to tell about it. The problem is that I don't know which compressors I can buy (cheaply) and which hoses I can buy (cheaply) are going to be safe.
Perhaps you can get the air tested, perhaps you can do A LOT of really good research, but you really need to do one or the other or both. You can't just buy off the shelf industrial stuff and expect this to go well. It might, but it might not, and the very real consequence is death.
I know a local boat diver that uses an industrial compressor and a long diving hose and is still alive. His setup is okay, but it's hard to know which ones are and which aren't. Even if you bought the same brand/model as he did, they may have outsourced parts to someone else and it may all have changed. It can be done, but tread lightly and know the risks. Take a SCUBA class, do your homework and/or get the air tested and definitely try it out in your living room for hours before going deep with it.
Lets watch a video of untrained divers using a hookah setup in very shallow water.
Did everyone notice how the first thing he did was remove the regulator? That is a reflex to try and move things away from your face in order to get more air. Without training that normal panic reflex (and others) will get you killed.
Be safe, and if anyone does figure out how to do it safely please post a detailed how-to!