"It will take a leap of faith," he said.
Mr Williams and two taskforce staff saw the Australian Employment Covenant scheme in February on a five-day trip funded by Sir Stephen Tindall's Tindall Foundation, which has also sponsored a "youth connections" scheme to help young people into work in Auckland.
The covenant was launched in 2008 by mining magnate Andrew Forrest, who grew up with Aboriginal children in a remote area of Western Australia. It aimed to draw 50,000 job promises, but has already surpassed that with 61,717 jobs promised by more than 335 employers.
Mr Williams proposes promises called Job Opportunity Bonds (JOBs). Employers would say when a job would become available, specify the required criteria, and promise to hold the job for someone referred by the local community with the necessary qualifications.
"Step one is the community sends a message that it wants to get involved. The taskforce trains the mayor and helps establish a local steering group of education, training providers and employers to undertake a stocktake," Mr Williams said.
"Then work out how to work with the training providers so the young people will be prepared to the standards the employers are requiring."
Employers and Manufacturers Association training officer Mike Burgess said many employers supported local initiatives such as Auckland's Youth Connections and he believed a national target of 20,000 job promises was achievable.
Motor Trade Association spokesman Ian Stronach said car dealers and repair shops faced "a greater demand for better people than an ability to supply" and were keen to participate.
Trust Waikato chief executive Bev Gatenby said her trust was working with the WEL Energy Trust and DV Bryant Trust to help fund any local Waikato initiatives to create jobs for young people.
Kawerau Mayor Malcolm Campbell said many mayors were wary of committing to a numerical target.
Employment Minister Steven Joyce said his officials were still working out what 20,000 jobs would mean at a local level to prepare a revised memorandum of understanding with the mayors taskforce.