Snap a Shimano chain pin without pliers?
A quick-link type product is probably the fastest, easiest, and lightest option to repair a chain on the roadside. I personally have not had any trouble, including excess noise, when using SRAM's or KMC's quick link product on my 9 speed Shimano chains. 

To specifically answer your question, use a couple of hex keys that are next to each other on the tool. Unfold the pair so that one key is straight out, the second just short of straight out. You now have the two keys forming a narrow "Y" shape. You'd use this to snap off the leading pin by placing the fully extended key underneath the pin right at the score of the breakpoint. Position the angled hex key on top just outside the line of the under-key.  Wedge the pin firmly--scissor-like--maintaining the hex keys relative positions of under the break point and on top &amp; outside of the line of the under-pin key.  Grip firmly and twist the system such that the wedged pin is levered around the bottom key--and at the pin's break point.  Wedge, twist, snap.