How to break reinforced Shimano pin?
Ok, I did it! :-D I took two plates of steel, drilled a little hole in one of them (for the pin), then put the chain between them (pin goes through the hole of course). This served as vice, but because it was not mechanically clamped I could control the force.

Then I used pair of pliers, and without a sweat, pin snapped.

I used the same chain before, but I used regular pin, after a year it came out of the chain (partially), thus this time I used reinforced one. We'll see how good it is...