You could use the Cell Change event to change the font to a 'Webdings' font after the user changes the cell. Then all anyone needs to do is select the cell and view the text unaltered in the formula bar... So you could turn off the formula bar, but then anyone could copy the text and view it in a clip-board viewer to see whats typed. Like Dave suggested, you might consider using a Textbox or Textbox on a userform. With the Textbox you can set a Mask option, and select the caracter to use as the mask character.
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