How to write to a debug console in VB6?

This isn't expected to be the accepted answer because Debug.Print is the way to go for IDE testing.

However just to show how to use the standard I/O streams easily in VB6:

Option Explicit
'
'Reference to Microsoft Scripting Runtime.
'

Public SIn As Scripting.TextStream
Public SOut As Scripting.TextStream

'--- Only required for testing in IDE or Windows Subsystem ===
Private Declare Function AllocConsole Lib "kernel32" () As Long
Private Declare Function GetConsoleTitle Lib "kernel32" _
    Alias "GetConsoleTitleA" ( _
    ByVal lpConsoleTitle As String, _
    ByVal nSize As Long) As Long
Private Declare Function FreeConsole Lib "kernel32" () As Long

Private Allocated As Boolean

Private Sub Setup()
    Dim Title As String

    Title = Space$(260)
    If GetConsoleTitle(Title, 260) = 0 Then
        AllocConsole
        Allocated = True
    End If
End Sub

Private Sub TearDown()
    If Allocated Then
        SOut.Write "Press enter to continue..."
        SIn.ReadLine
        FreeConsole
    End If
End Sub
'--- End testing ---------------------------------------------

Private Sub Main()
    Setup 'Omit for Console Subsystem.

    With New Scripting.FileSystemObject
        Set SIn = .GetStandardStream(StdIn)
        Set SOut = .GetStandardStream(StdOut)
    End With

    SOut.WriteLine "Any output you want"
    SOut.WriteLine "Goes here"

    TearDown 'Omit for Console Subsystem.
End Sub

Note that very little of the code there is required for an actual Console program in VB6. The bulk of it is about allocating a Console window when the program is not running in the Console Subsystem.

Use debug.print. But there is no console on a VB6 application, that will print to the debug window.