How to set a user selected in user picker

Hi All,

Is there a way to set  default selected user in user picker. I have overlayed user picker and customized it to pull user from given group. User picker by default display blank field and upon selection sets the selected user to the textfield. Is there a way to tell (specify) userpicker to display a specific user from the list to be set in the textfield?

Currently i am looking into render.jsp of user picker to check this can be achieved.

Any help is really appriciated.