Zoom In and Out a Page

Hi,

I trying to develop an android application.

i create a page an it contains only a text.

<s:Scroller width="100%" height="100%">

    <s:VGroup horizontalAlign="left" paddingBottom="5" paddingLeft="3" paddingRight="3"

              paddingTop="5">

        <s:Label width="100%" fontFamily="Verdana" fontSize="12"

                 text="Hello World This is my text page This is my text page This is my text page This is my text page This is my text page This is my text page This is my text page This is my text page"

                 height.landscape="100%" textAlign.landscape="left"

                 height.portrait="100%" textAlign.portrait="left"/>

            </s:VGroup>

    </s:Scroller>

how can i zoom in and out process at this page (text) using a two fingers?

thanks

peace