Turns out what I want to do is not possible - any references to Google Maps API has to be removed completely from the app. See response from the BlackBerry forums :
"No, it's not going to work. Save yourself time trying to find a fix, and just copy your project to a new one and make the needed changes for blackberry. If you are using source control, then you can try branching off for that probject.
By the way. If you want Google maps in your app, it can be done using a webview and Google's javascript API."