I'm with Scrap, well to a point as I don't really know what 'oral and ocular cavity' relates to (I thought I'd be more likely to find these on those 'other' forums that I visit!) Anyways, Tyson used to use slips to brilliant effect, mixing them in with various combinations to deliver crippling damage on opponents. All of his early work slipping was dictated by the legs, not the waist. As soon as his limited head movement was generated by waist movement, he started getting clipped with alarming regularity.

Set 2 simple rules:

1) The slips I perform will be technically perfect. I will assure technical perfection by using mirrors to ensure form is correct and the movement is as economical as possible, and
2) I will slip before and after every shot/group of shots. Do this during shadow boxing, bagwork, pads and sparring.

Ropes tied across the rings are good, as was Wayne's suggestion of a swinging tennis ball on a string.

Good luck

Fran

PS - remember that slips and rolls are also excellent methods of 'feinting' an opponent to prompt a reaction...multi-purpose skill!