Just got the Warclaw this afternoon after grinding about Five Hours in WvW to
So the process is to Get all the items in the Warclaw Achievement by grinding WvW stuff, enable the Warclaw in the Bottom Left area of the WvW panel. Then Activate the Warclaw Reward Track and grind that bar all the way to the end to get the Warclaw Helmet. Then the Warclaw Certificate shows up in the Vendor for 8 Gold. Buy that and use it. And Voila, you have the Warclaw mount. Sigh.