How to work with devices which are not assigned a letter (such as the Apple Iphone — when connected via the cord)?

In spite of that device - if it is disk, it is possible to work as with a disk, if the network path as a network address. But there may be other options - for example, this may be just the program window that opens is the driver.

Apparently the standard tools can not work.
Look for the manufacturer of the device any command line utilities to work with it. Not the fact that they are in nature.

Another option is to use PowerShell, as far as I know there is possible to organize copying, for example with the iPhone and your device can spin the same way.

PS: as far as I remember the scanners haven't allowed myself to write, except to change the firmware with the help of special.utilities.