You can't format the textbox only the output.
you could have the user enter 10112000 and then format it before you display or save it.
Format(Text1.text,"mm/dd/yyyy")
To only allow users to enter information in certain ways
you could use the MaskeditBox. Add one to your project and press F1 to get more information on MaskEditBox.
"A myth is not the succession of individual images,
but an integerated meaningful entity,
reflecting a distinct aspect of the real world."
___ Adolf Jensen