Using the Connect As functionality on a Map Printer Action to map to a printer shared in an untrusted domain will fail to map the printer.
Due to the nature of the AddPrinterConnection API that is utilitzed by Environment Manager, this fails because the client machine is not part of the target (untrusted) domain.
A workaround is available by first mapping a drive to the target server by using the Connect As functionality, then as a child action or child node map the desired printer (not using the Connect As feature).
By mapping the drive first, the authentication has taken place and mapping a printer afterwards leverages the authenticated account.
The drive can be unmapped if required once the printer connection is made.