I've mounted and removed the 003 pads a few dozen times. While they will certainly need to be repaired shortly, I've had good success
gently stretching them by hand before I start trying to mount them. I then evert them, just like folks do for the 840 pads, and pull them over the cups, starting at the top of the cup and working down, leaving a bottom "corner" until last. From there, I work to stretch the pad by pushing on the flap from the inside of the hole, not pulling it from the outside. In the picture below, you can see that my right hand is working through the pad hole, while my left hand holds the rest of the pad in place.
All of my tears are along the top, bottom and sides of the pads and that's why I suggest leaving one of the corners until last. These areas seem to be able to withstand the stretching the best. But eventually, something will give and you'll probably get a nick which will turn into a tear. YMMV.
In my case, I really needed the 003 pads to get a good seal and a correspondingly good dose of bass. Until I started using them, I tried stock, 840 and JVC RX900 pads and really couldn't understand what all the "massive sub-bass" talk was all about. Now I get it completely.
EDIT: warming the pads may help stretch them and ease them onto the cups. But I'm not sure if it really helps much or just makes the pads more susceptible to nicks. Again, YMMV. Like I said, I've mounted them several times, but despite ongoing care, I'll still need to repair them.