Changing the Web Application Pool Identity using PowerShell

Hi,

 I writing Powershell scripts to do few setups in dev environment (like New web application, Enabling Self Service Site Creation, Changing My site Host Location, Changing the Application Pool Identity). I am stuck at the part of changing the application pool identity for the web application. Is it possible to change the applicaiton pool identity (which we usually do it through 'configure Service accounts' in CA) using Powershell?.