If you have just a few greetings to save, it's easiest to just use the Media Master control in the SA to save them out as WAV files and then reimport them in the new system. If you have a bunch of information you want to save, the only other automated mechanism to do so is the BulkImport/Export tools on AnswerMonkey (in this case off the 2.x tools page). This saves most everything, though, not just greetings. The help files and web page on AnswerMonkey cover the details of how these tools work.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...