"Manual Sync When Roaming" is unavailable.
The "manual sync when roaming" option may be grayed out because your Exchange server has set that option as a policy that TouchDown is automatically complying. More information on this Exchange ActiveSync setting can be found here: http://msdn.microsoft.com/en-us/library/ee160447(v=exchg.80).aspx
For IT Professionals: When viewing the EAS policies, press where it says, "allow". If this is checked On, then TouchDown will enable the "Manual Sync on roaming" checkbox so that the user can uncheck it. This will allow those users to decide for themselves if they'd like to use direct push when they are roaming.
You can view what policies are being applied to your device by going to TouchDown Advanced Settings and pressing the "Security Policies" button.