it is possible, but u need to do a lot of. But I think its not feasible to use dongles, First u dont have drivers for microcontrollers, u have to write ur own which u cant because the dongle manufacture dont provide their dongle hw details. So u goona need a bluetooth radio device which can be hooked to microcontroller through serial interface, e.g. bt radio chip made by ericsson or national semicondutor.
On mouse side, I think there can be alternatives to interface it with microcontroller. In essence you have to programs it to handle its interface to mouse. You might need to read standard mouse interface specification to understand what's going on.
I will suggest try to collect as much as knowledge about the things before you starting.