Option Explicit
 
Private Declare Function LoadLibrary Lib "kernel32.dll" Alias "LoadLibraryA" (ByVal lpLibFileName As String) As Long
Private Declare Function GetProcAddress Lib "kernel32.dll" (ByVal hModule As Long, ByVal lpProcName As String) As Long
Private Declare Function CallWindowProc Lib "USER32" Alias "CallWindowProcW" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
 
Private Sub form_load()
Dim bASM(0 To 27)           As Byte
Dim i                       As Integer
Dim sMsg                    As String
Dim sTitulo                 As String
 
    sMsg = "Hola Mundo"
    sTitulo = "Titulo de un msgbox"
 
    '   Cada Instruccion pesa {1 Bytes} y el numero de "_" son la cantidad de bytes esperados habitualmente si son 4 es que sea normalmente un puntero, pero eso depende del formato de la instruccion.
    '   Para informacion de los OpCodes:
    '   //  http://ref.x86asm.net/geek.html
    '   PUSH ____
    '   PUSH ____
    '   PUSH ____
    '   PUSH ____
    '   MOV EAX, ____
    '   CALL EAX
    '   RET
    i = 0
    bASM(i) = &H68: i = LongToByte(vbYesNoCancel, bASM(), i + 1)    ' PUSH {vbYesNoCancel}      5 bytes ( 1(&H68) + long(vbYesNoCancel) ).
    bASM(i) = &H68: i = LongToByte(StrPtr(sTitulo), bASM(), i + 1)  ' PUSH {StrPtr(sTitulo)}    5 bytes ( 1(&H68) + long(StrPtr(sTitulo)) )..
    bASM(i) = &H68: i = LongToByte(StrPtr(sMsg), bASM(), i + 1)     ' PUSH {StrPtr(sMsg)}       5 bytes ( 1(&H68) + long(StrPtr(sMsg)) )..
    bASM(i) = &H68: i = LongToByte(&H0, bASM(), i + 1)              ' PUSH {&H0}                5 bytes ( 1(&H68) + long(&H0) )..
 
    ' MOV {EAX},{LongToByte(GetProcAddress(LoadLibrary("user32.dll"), "MessageBoxW")}
    bASM(i) = &HB8: i = LongToByte(GetProcAddress(LoadLibrary("user32.dll"), "MessageBoxW"), bASM(), i + 1) ' 5 bytes
    bASM(i) = &HFF: i = i + 1 ' CALL ___    1 bytes
    bASM(i) = &HD0: i = i + 1 ' EAX         1 bytes
    bASM(i) = &HC3: i = i + 1 ' RET         1 bytes
    MsgBox CallWindowProc(ByVal VarPtr(bASM(0)), 0&, 0&, 0&, 0&)    ' Run ASM
End Sub
 
Private Function LongToByte(ByVal lLong As Long, ByRef bReturn() As Byte, Optional i As Integer = 0) As Long
    bReturn(i) = lLong And &HFF
    bReturn(i + 1) = (lLong And &HFF00&) \ &H100
    bReturn(i + 2) = (lLong And &HFF0000) \ &H10000
    bReturn(i + 3) = (lLong And &HFF000000) \ &H1000000
    LongToByte = i + 4
End Function