How to seamlessly login to another application from PeopleSoft SSO

Hi PS experts!
Currently we are on PeopleSoft 9 release and tools 851. We log-in to PeopleSoft application using SSO credentials. After logging in, from with-in peoplesoft application we have menu which take us to another application seamlessly without entering any log-in credentials by passing the PSTOKEN ( in Component Pre-build peoplecode).

Now after upgrading to PT854 we would have to achieve the same by passing Siteminder token intsead of PS token.

Can someone explain clearly how can this be achieved??

Thanks in advance for your help!