This is a VAR Tyre-Tool - from the UK. These are quite portable and make mounting the meanest, nastiest clinchers a breeze on any rim. One side straddles the side of the rim-wall you already have the tire-bead mounted on. The other side goes over the tire and hooks the bead you are trying to get mounted. Then you just pull back and the tool pulls the bead up and over the rim-wall - mounting the tire.
These were available here - out of stock currently, but ask Al when he'll get them in. They are worth the wait:
http://cgi.ebay.com/VAR-Super-Tyre-Tire-Tool-New_W0QQitemZ310141789105QQcmdZViewItemQQptZCycling_Parts_Accessories?hash=item4835e423b1&_trksid=p4 634.c0.m14&_trkparms=|301%3A0|293%3A1|294%3A30
Here's a photo:
