You do not necessarily have to use a user form for that functionality (it probably makes for a neater user interface if you do though), an ActiveX TextBox placed on a worksheet (maybe hidden/unhidden as needed) could also be used because it too has the PasswordChar property.I had the same question at one time and the answer is you need to create a user form, the standard input box will not work. You create a text box on the form in which to enter the password. When you look under the properties for the textbox you will see a box labeled PasswordChar and you pick a character.
You do not necessarily have to use a user form for that functionality (it probably makes for a neater user interface if you do though), an ActiveX TextBox placed on a worksheet (maybe hidden/unhidden as needed) could also be used because it too has the PasswordChar property.