Hi mrcwillis,
This kind of sounds like you are doing filesystem archiving. Are you trying to migrate the archives or the placeholders? If you're using the placeholders then take a look at the EV utilities document. 289862.pdf talks a bit about how to use `fsautil` with the -m switch to migrate placeholders.
Moving the archive is also pretty easy. Take a look at TECH35742 support article at Symantec. I've migrated to other servers and archive locations. The steps are well described.
If you are moving compliance content then you will probably want to have this done by a third party company to address chain of custody and data spoliation. There are a number of qualified consulting organizations who are well equipped to help with this.
Thanks,
Nathan