I got it to work by embedding all of the CR JARs into the EAR itself. Didn't try using modules.
It sounds like you're just updating an app to run on AS7, but in case you're not and you actually have a choice, DON'T USE CRYSTAL REPORTS. Pick something else like BIRT or Jasper. CR is a nightmare to deal with in Java. Documentation is almost nonexistent, the Javadocs (if you can find them) contain no useful information, and the source code is obfuscated so you can't even try to figure out what's going wrong using the stack trace. I'm using BIRT on another project and it's a million times easier to work with.