Hi Lou,
I am packaging a headless server image (XD Packaging) so I do it via the Packaged Image Browser, and add these entries to the Packaging Instruction using the menus there.
But you can also implement a class method on your Application, Look at this example from AbtXmlSchemaSupportApp class>>#packagingRulesFor:
packagingRulesFor: aPackagedImage
"Classes in this application can be created dynamically via an XML file. Therefore, do not reduce the contents of this
application "
aPackagedImage doNotReduceSubApplicationNamed: self symbol
I guess this says it all.
Joachim