Not aware of any special tool that holds the crank in place, but maybe there is one. I bought sprocket lock tools at NAPA (cheap, may $15-20/tool?). So you use the lock tools to hold each pair of sprockets in place while you route the belt. However, I had big trouble with this job. The trick is to get the belt on very tight (and I mean tight), so that the only slack is between the inlet sprocket (by the firewall) and the belt tensioner). I learned a trick while doing this. I offset the timing mark on the exhaust sprocket about 2 teeth then routed the belt from the crank and over the sprockets, and clamped the the belt to the sprockets. Stopped there and did not route the belt down to the WP. Then I just a wrench and turned the sprockets into their timing marks. By doing this, belt now very tight between sprockets and crank. Then I continued to route the belt over WP and up over the sprockets. Used the same technique there ,and offset the timing marks, but not as much as on the exhaust side. Used the wrench to turn the sprockets into their timing mark positions, being carefu to not pull to much so that the inlet sprockets started turning too. After a few trial and errors i succeeded and the timing marks on both side lined-up perfectly.