using arduino Uno as USB to serial converter

I want to control the movement of my robot (named "hUnter") with optical mouse. The USB mouse would be connected directly to the robot's brain (arduino Uno). On reading USB protocol specs, I realized that I will need to convert the data(in USB protocol format) from the mouse to simple serial communication format. USB protocol seemed a daunting task, and I thought of circumventing the problem, but I have decided to go along this tough way so that i can learn new things.

Hence I have decided to make a simple USB to serial converter in the process. I understand that I need special hardware and the driver (software) along with another microcontroller to enable it to do this form of communication.

But then I encountered terms "VendorId" and "ProductId". My question is - "do i need these IDs to design/develop a simple USB to serial converter? (My USB to serial converter is never going to interact with a PC and is supposed to do only 1 job which is - receive data from optical mouse)

If you have some comments/recommendations, other than the solution, please mention that too.

Sounds like a lot of work but completely understand wanting to do it the hard way!

If you're taking the mouse apart, the "easy" way might be to intercept the signal from the optical sensor(s) before they get converted to USB and pipe those direct to the Arduino... interesting proposition either way - looking forward to hearing about your progress!