I attempted this several years ago on a simple robotics project unrelated to FIRST. I ran into several problems.
The mouse must see texture as it compares one image to the next to determine motion and direction. Good imaging is important so before you spend a lot of time make sure the official carpet is not of a nature that treads, dirt or other debris might get caught in the optics as the mouse moves along the floor.
Another test is with the optical mouse you plan to use. There are many makers out there. You may want to plug it into a computer, use a mouse pad, and check repeatability. In other words. pick a spot on the mouse pad. look at the location of the pointer on the screen, move the mouse away and them back to the start point and see what kind of error you get on the screen. This will help you determine max speed your robot can go with that particular mouse.
This doesn't directly address what you are doing but it's an interesting hack and might help.
http://www.contrib.andrew.cmu.edu/~t...ision_Project/
I DID see a small robot that used a mouse for guidance, but that was on a smooth, hard floor with texturing. Parts of the floor I tried to transverse were too smooth for the mouse to pick up the motion and thought it was standing still.
Good luck
Steve