Flash as3 scrollpane source value changing dynamically

Hi,
I added one movieclip, in scrollpane dynamicallly. In The movieclip, one text field is there, in that i have to change the text through xml…when clicked on next and back buttons text has to change… How…Please help me… Main problem is how to , i take the text field…

ex :
scrollpane.my_mc.txt.tex"kkkkkkkkkkkkkkkkkkkk"

Pleasse help…