Low level CD-Rom emulation on AT90USB162. How?

Question

Helpdesk

Faced a tough problem.
I am making a USB device based on AT90USB162 , on which it is necessary to emulate a CD-Rom drive with the output of files from a separate eeprom circuit.
The Internet is full of programs that create emulation, but in fact I did not find low-level information.

• Who knows how this emulation happens?
  
• Is it written to the memory chip at the file level or does it flash the data about the device type in the main MK?
  

In general, I can’t understand how it works and how it can be organized .. I work in CodeVisionAVR .
I hope for your help..