Include the below to your package.json file and npm install
"pliers-webpagetest": "timjgleeson/pliers-webpagetest"
In your pliers.js add:
pliersWebpagetest = require('pliers-webpagetest')
...
pliersWebpagetest(pliers, taskName:string, url:string, apiKey:string, location:string)
Example:
pliersWebpagetest(pliers, 'runWebpagetest', 'http://www.clock.co.uk', '1234abcd', 'Dulles:Chrome')