To change a property for one control on a page, use code similar to the following. This example refers to a TextBox on page "P.2" named "TextBox1".
Item.GetInspector.ModifiedFormPages("P.2").TextBox1
To cycle through and change the Visible property on all controls on a page, use code similar to the following.
Set myPage = Item.GetInspector.ModifiedFormPages("P.2")
For i = 0 to myPage.Controls.Count - 1
myPage.Controls(i).Visible = False
Next