Joseph DeVore's Blog: Select multiple options in a CFSELECT (when using MULITPLE="yes") based on list of index positions.

<cfform format="flash" name="mulitselect" width="300" height="300">
   <cfformitem type="script">
      var selectOptions = function(selectBox:Object, indiciesList:String):Void {
         var options:Array = indiciesList.split(',');
         selectBox.selectedIndices=options;   
      }
   </cfformitem>
   <cfselect name="mySelectBox" multiple="yes" size="5" >
      <option value="option 1">1</option>
      <option value="option 2">2</option>
      <option value="option 3">3</option>
      <option value="option 4">4</option>
      <option value="option 5">5</option>
   </cfselect>
   
   <cfinput type="button" name="q" value="SELECT OPTIONS" onclick="selectOptions(mySelectBox, '0,1,3')">
</cfform>