i think that u are using WSRP.
You can put an apache server between your consumer and your producer application.
But the Apache Server is not really a solution because the apache server would be between the portal and the protlet provider. Though the switch between portlet providers would be easier with the Apache, it wouldn't be enough.
Indeed if one developer add a redirection in the Apache configuration to point to his own portlet provider and debug his portlet, then all the other developers would use its portlet provider.
I would rather think of a listener in the portal itself if possible.
Thanks for your help