Where do I install the Enrollment Point if a user enrolling Mobile Devices with ConfigMgr has an Active Directory account in a different, untrusted Forest to the Site Server?

Where do I install the Enrollment Point if a user enrolling Mobile Devices with ConfigMgr has an Active Directory account in a different, untrusted Forest to the Site Server?

Where do I install the Enrollment Point if a user enrolling Mobile Devices with ConfigMgr has an Active Directory account in a different, untrusted Forest to the Site Server?