To adopt the WTB plan, you need either Leipart or Woytinsk (part of the Labor faction) and then use either of their Advisor actions to obtain support for the plan among the unions. Then, via the event "The Economic Crisis", choose the Labor faction option. Finally, once you control the Economic and/or Finance Ministry, use Woytinsk's Advisor ability to institute it.
Also I think you can go for a "street-fighting" if you focus funding on the Reichsbanner and choosing to fund the youth organizations; supporting the Left faction may also help but I'm not sure