Some possible methods:
1) Observe species popping into existence out of thin air. This would lend evidence to supernatural creation events.
2) Observe absolute barriers between different "kinds" which cannot be crossed, i.e. traits which cannot be mixed (you either live on land and breathe air, or at sea and breathe in liquid; you either fly, or you don't, and no one has half a wing, etc.)
3) Demonstrate the "irreducible complexity" of some living system. (For example, I believe Dawkins pointed out we should not expect to find any organisms on other planets with wheels, because it would be impossible to make the wheels and spokes independent without breaking the arteries nourishing the tissue.)
4) Observe that designs are always optimal or "intelligent".
5) Use physics theory/experiment to show that "information" always decreases and is never created by the laws of physics alone. (I.e. a violation of the laws of physics -- a supernatural event -- is required.)