Hi Carlos,
I'm not sure I quite understand what you want to do but you can certainly create different mixes routed to different (stereo) outputs by using the 8 bus lines. With these you could have 4 stereo mixes or a combination of stereo and mono mixes. You would control the level of each channel in a particular mix with the relevant bus send control for that channel, and the overal output level with the bus output level controls.
Cheers, Ian.
