A: 

hi, you can use the AxisRenderer to do this . search the flex 3 api ,key word is "AxisRenderer "

then go to the style you will find "tickPlacement" .

the following is one example:

<mx:verticalAxisRenderers>
    <mx:AxisRenderer axis="{verticalaxisid}" tickPlacement="outside" />
</mx:verticalAxisRenderers>
yay