You can use this idea for ANY FIGURE with an eye 'bone'. You can look at my settings to make it invisible in renders, or you could just make it invisible when you want to render. I chose to use the right eye, I set the figure to zero. I chose a primitive prop. I aligned it to the eye by showing the 'origin' (green cross) of the primitive prop, then opened joint editor, select the eye. Then I set the prop centre to the eye centre. Moved the prop Ztran to about arms length from the eye. scaled it, from 'Editing tools' chose grouping tool. Made a new prop, named it. Configured it in the Material room, then Display>Element style. Then Object>lock actor. Parented it to the eye. Bingo! Then, deleted the original prop, saved the new eye prop as a 'smart prop'. The figure needs to be zeroed first before making the guide or when the figure is reset after a pose the smart prop will move to some odd position.