set find text preferences to nothing 
		set change text preferences to nothing 
		set find what of find text preferences to "aaa" 
		set change to of change text preferences to "BBB" 
		set myFoundItems to change text 

tell application "Adobe InDesign CS4" 
  set find text preferences to nothing 
  set change text preferences to nothing 
  set find what of find text preferences to "aaa" 
  set change to of change text preferences to "BBB" 
  tell document 1 
    set myFoundItems to change text 
  end tell 
  set find text preferences to nothing 
  set change text preferences to nothing 
end tell