Workflow rule involving permission access levels

Hi, we appreciate the newly released permission access level functionality, especially in combination with user profiles. I am currently trying to set up a workflow rule that sets the permissions for newly created projects depending on the project type. Eg.

A newly created development project automatically has the permission access level set that everyone with the profile "development project managers" has access to it.

I can't find the permissions field when I try and use the update field function when I try and make the workflow rule. 

Thank you in advance for any help.