Linking to another SAP Portal from within EP5

We are trying to create a link to another separate SAP portal

instance from within our Main SAP Portal.

Is there any way to open up a link from an iView or service, that

will open up another portal session (to a completely separate portal

instance). We tried to do this by creating a .NET iView whose URL

pointed to our desired portal instance. Everything was fine when we

tested our iView in preview mode. However, when you place the iView

on a page, and then navigate to it, the iView correctly takes you to

the portal, however you can no longer navigate from within your main

portal. This has to due with the inability to maintain the logon

ticket for your originating portal. Is there a JSP or ASP command

that will allow you to create a window in a separate memory session

so that an entirely separate logon ticket is issued each time you

navigate to your other portal, hence allowing you to navigate to

another portal instance within your current portal. (i.e.

window.open will not do this) ?