One option is to just download the resources from the net as part of an initialization phase when your app is first launched. This would allow you to store your resources to the SD card (if present) or to built-in flash if SD isn't there. The big downside to this is that it requires networking which, ironically, can be tricky on a BlackBerry.
Another option might be to create a "library" project which simply contains all your resources (analogous to how language resources are used). You'd then add that project to your build and have it installed along with your app. When your app starts you read all the resources out and save them to the SD if it's there, and then use CodeModuleManager to delete the library module.
Of course, in any event, you need to bear in mind that if the user swaps their SD card your app might get rendered useless.
