When running the Identity Manager installer, one of the options you have is a checkbox to install the Identity Manager extensions for Siteminder. This article describes when you need to check it.
Environment
Release: Component: IDMGR
Resolution
You only need to select this option if you are:
Integrating SiteMinder with Identity Manager
AND
Going to use SiteMinder for Advanced Password Services, complex Password Policy Management such as managing password expiration rules etc. (that cannot be otherwise done via Identity Manager alone).
Note that if you are only going to use Siteminder for authentication and authorization, then you do NOT need to install the Identity Manager extensions on your policy server machine.