With a slow rolling plane there is a way of doing it easily. A little extra speed helps.
Also not sure what you mean by "loosens up". All start with a properly trimmed plane that will fly straight and level hands off.

Method: From level attitude raise the nose just slightly and neutralize elevator in that attitude. Quickly throw FULL aileron in the desired direction while being careful NOT to move in elevator control. As the plane rolls the nose will naturally drop a little, don't worry about it yet. As the plane approaches fully inverted add a little "down" elevator sufficient to place the nose gently back to the slightly nose high position. Shortly after passing fully inverted you MUST be back to neutral elevator or the plane will be wallowing around. You can see the elevator must be quick but gentle at the same time. Continue the roll and as you approach wings level you will once again need a little "up" elevator to bring the nose back up. With slower roll rates you may even want to add "top" side rudder to hold the nose up.