We have the following setup
Oracle Primavera P6
Oracle Primavera CM
Users login to Sharepoint using their domain account. Sharepoint has links inside that lead to Primavera P6 and CM. Following that link, the user should be able to get to Primavera without authorizing to Primavera again (he was already authorized at Sharepoint).
Important note: there are users who are working on a non-domain computers and they login to Sharepoint using domain account. These users should be also able to get to Primavera based on Sharepoint authorization.
What I have found is that the following components should be installed: ISAPI Web Gate + Oracle Identity Server, but feel free to provide your solution and setup.