Add a "Choose Role" on Logon Page

Hi,

<b>Is it possible to add a "Choose Role" on the portal so that when the user enters, it only shows up the desired role and hides the other ?</b>

I know of the possibility of directly accessing a special role :

<b>http://<server>:50000/irj/portal?NavigationTarget=ROLES://<pcd_path_without_pcd:></b>

but this is not what I am looking for.