Now, I don't know everything about throwing a curve, but I do have some knowledge.
Over the summer, I attended PT for my hip with a therapist who is really in to baseball. He attended lectures by Dr. James R. Andrews and others at ASMI, and had printed some copies of the packets he received and gave them to me. One of these was about the increase of in throwing arm injuries in youth players. I had 2 packets that discussed the curveball, and of course I did not find the one I wanted but this one will suffice. Testing done found that a properly thrown curveball puts less stress on the arm than a fastball. The packet I had a picture of says "no more stress", however the other one said "less". I'll continue to search for the other packet, but here is a picture from the one I have:
Here's the deal with throwing it properly: if your release looks kinda like this:
With you "hooking" the ball to throw your curve like many people do you are killing your flexor mass, and also increasing the stress on the UCL.
A proper curveball is throwing it with flexion of the wrist. That's how. Not supination of the arm. The supination to probation movement is very important to elbow health, and anything compromising that runs the risk of compromising elbow health.
So, this means that the only way to throw a good curve, if you throw it properly, will be to have good spination while your arm externally loads, so that the movement of external to internal rotation is very quick adding rpm to the ball. Without stepping on others' toes too much here, the idea to forcefully supinate the arm only becomes nessecary when you don't have a good arm path.
I'm not sure how much you know about this, so I tried adding minimal background. Because of this, how I wrote it may be very ambiguous. If you have any questions please ask and I'll add whatever info I need to, so that I may clarify - whether it be links to studies, or just explanations of what I wrote. I can also always record the right and wrong way and upload it.