Sergio,
Assuming you want to do a rolling horizontal figure 8 with "a lot of rolls, try this mental picture.
Imagine you are looking down on your model plane from directly above it. Starting from a straight and level flightpath, you begin by rolling to the right. As the plane rolls right 90 degrees, canopy is to the right, so that the wings are vertical to the ground, you pull up elevator and release elevator back to neutral as the plane rolls inverted. As it continues to roll right to 270 degrees, canopy is to the left and wings are verticle to the ground, you push down elevator and release elevator back to neutral as the plane rolls upright. You continue this procedure until you have completed a horizontal rolling circle, which is the first half of your desired horizontal rolling 8.
Now you reverse your roll and start rolling to the left. Continue using elevator when the wings are vertical with canopy left (up elevator) and canopy right (down elevator). Continue this until you have completed a rolling circle to the left, which is the second half of your desired rolling horizontal 8.
This maneuver can be done using up elevator and no down elevator.
Try it both ways and see which you prefer.
Remember to do this while flying 2 mistakes high.
Regards
JC