changing the owner of a project in project server 2010 using PSI

Hi All,

Please help on the below scenario 

I have successfully created a project in project server 2010 using PSI.But by default the project owner is always administrator

How can i change the owner on fly using PSI with the Custom user who already have a right on project server 2010 to create a project

Is there any method which can be used to give username for owner columns??