PaulS, anyone would think you are trying to be difficult
Yes, this is possible, you can have your arduino take data from the photoresistors (connected in a voltage divider to the analog inputs - you only need an extra resistor for each photoresistor) then you can send serial data to your computer (I will assume you are using Windows as you have not said) and use software such as Serial Keys or AAC Keys to emulate mouse movements.
Now you need to go do research based on that info
This idea will however, not be very accurate and will not work if the ambient lighting changes.
PS, just for your info, it's arduino...