How to modify user bill rates and add tasks to a Zoho Books project using Zoho Flow

How to modify user bill rates and add tasks to a Zoho Books project using Zoho Flow

Hi, 

I want to create a flow which adds users to a Zoho Books project and then sets their bill rate.  I also want to add tasks to the project.  How can I do that?  The current pre-set functions for Zoho Books projects does not allow for these fields to be added / modified.  Is there a custom script that can be written to do this?