Don't do any of this while "btcprocess" (discussed in the BTC setup docuemntation) is running. That script manages the Jaz drive automatically, and could become confused if you start using it on the side as well.
To use the Jaz drive, just make sure it is hooked up to the laptop as documented in the aforementioned BTC setup file, and turned on.
The jaz drive will be mounted at /jaz. There will probably be a directory /jaz/deep in which you, as deep, can muck around.
Important! Don't just pop that sucker out. To do so could corrupt its filesystem, making you sad! Always follow this procedure.