На onRollOver вешаем вызов фильтра свечение.

Код AS1/AS2:
import flash.filters.DropShadowFilter;
import flash.filters.GlowFilter;
var filter:DropShadowFilter = new DropShadowFilter(distance, angleInDegrees, color, alpha, blurX, blurY, strength, quality, inner, knockout, hideObject);
var filterArray:Array = new Array();
filterArray.push(filter);
mov.filters = filterArray;