It's possible!

Copy the following code to a module.

Code: VB
Option Explicit
 Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
 Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
 Public Declare Function SetTimer& Lib "user32" (ByVal hwnd&, ByVal nIDEvent&, ByVal uElapse&, ByVal lpTimerFunc&)
 Private Declare Function KillTimer& Lib "user32" (ByVal hwnd&, ByVal nIDEvent&)
 Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
 Public Const NV_INPUTBOX As Long = &H5000&
 Public WindowTitle As String
 Public Sub TimerProc(ByVal hwnd As Long, ByVal uMsg As Long, ByVal idEvent As Long, ByVal dwTime As Long)
     Dim EditHwnd As Long
     EditHwnd = FindWindowEx(FindWindow("#32770", WindowTitle), 0, "Edit", "")
     Call SendMessage(EditHwnd, EM_SETPASSWORDCHAR, Asc("$"), 0)
     KillTimer hwnd, idEvent
 End Sub
 Public Function PasswordInputbox(Prompt As String, Optional Title As String, Optional Default As String, Optional XPos As Long, Optional YPos As Long, Optional HelpFile As Long, Optional Context As Long) As String
     Dim ret As String
     If Title = "" Then
         WindowTitle = App.Title
         WindowTitle = Title
     End If
     SetTimer 0, 0, 1, AddressOf TimerProc
     PasswordInputbox = InputBox(Prompt, WindowTitle, Default, XPos, YPos, HelpFile, Context)
 End Function

Then, you may use it like this.

Code: VB
Dim a
     a = PasswordInputbox("Enter Password")
     ' example
     Label1.Caption = "Password entered : " & a

The project files are attached.
Attached Files
File Type: zip input-box (2.4 KB, 6 views)