You can do this from the command line, but it is probably not going to be worth the trouble, and will be quite a bit slower that what you are doing now
YOu would first need to gather the correct information. The heart of the connection between Data Protector and devices in the output from 'devbra -dev' run on the machine that is going to be acting as the media agent. In the 'Exch' area, you would get a list of serial numbers, which correspond to each drive in your SCSI-attached or SAN-attached library, and are in numerical order. You would need to know either the serial number o your drive, or its placement in teh library (ie, Drive-1, Drive-2, etc). This would be your Drive Index
The, view all the areas in the 'devbra' output that are labled Tape, and find the serial number that matches te eone you identified in the Exch area, and note the corresponding SCSI path of Device file
Had enough yet?
If not, then you would have to put these into a file in a very specific format. Fortunately, you can use an existing device to create a Template file by choosing a device, and running the command
omnidownload -device "[device name]" -file [filename]
For example
omnidownload -device "abc.com LTO4-D2" -file C:\temp\abc_d2.txt
In this example, the device name had a 'space' in it, so it would need to be surrounded by " marks
Edit the file to give the device a new name, add in the correct hostname and parameters, save the file.
Finally, run the command
omniupload -create_device "new device name" -file c:\temp\newfilename.txt
I will sometime use this method when added a device from the GUI just won't work, or I need to edit a device parameter that is not doable from the GUI< like the serial number. But, to my way of thinking, it is just way easier to do it from the GUI