DISK I/O
Eject a volume
The standard PBEJECT ought to work no matter what driver is in use. Drivers live underneath the filesystem.
There are two forms of "eject"; one is harsher, and doesn't leave the drive's volume entry intact. That one may eject in spite of open items.
Mars
I think the "eject & dismount" form actually does nothing if the volume has items in use, while the "eject but don't dismount" form will spit the disk out and show its icon "greyed-out" on the desktop. The catch is: it is also likely to cause a "please insert the disk" alert which you can't get rid of unless you actually re-insert the disk.
Rick