Highlight list box item

I have added new items to the list box. But I do not know how to highlight any particular item through AutoLisp. Please Help..

 

(set_tile key position) - set_tile expects position to be a string - so use itoa to format an integer. Here is the function that I use:

;;(fopset [tile key] [list of strings] [default value or list of values for multiselect])

(defun fopset (key lst val / i)
(client_data_tile key (vl-prin1-to-string lst))
(start_list key)
(mapcar 'add_list lst)
(end_list)
(cond
((not val))
((and
(= (type val) 'STR)
(setq i (vl-position val lst))
);and
(set_tile key (itoa i))
val
);single value
((listp val)
(f:remove_nils
(mapcar '(lambda (at)
(if (setq i (vl-position at lst))
(progn
(set_tile key (itoa i))
at
);progn
);if
)
val
);mapcar
)
);multiple select
);cond
)

(defun f:remove_nils (lst)
(vl-remove-if 'null lst)
)

Peter