Esa funcion funcionaria para vb6 no?
Intentaste depurar? que error te da?

 

  Const PAGE_READWRITE As Integer = &H4
    Const MEM_RELEASE As Integer = &H8000
    Const MEM_COMMIT As Integer = &H1000
    Const STANDARD_RIGHTS_REQUIRED As Integer = &HF0000
    Const SYNCHRONIZE As Integer = &H100000
    Const PROCESS_VM_READ As Integer = &H10
    Const PROCESS_VM_WRITE As Integer = (&H20)
    Const PROCESS_VM_OPERATION As Integer = (&H8)
    Const PROCESS_QUERY_INFORMATION As Integer = (&H400)
    Const PROCESS_READ_WRITE_QUERY As Integer = PROCESS_VM_READ + PROCESS_VM_WRITE + PROCESS_VM_OPERATION + PROCESS_QUERY_INFORMATION
    Const PROCESS_ALL_ACCESS As Integer = &H1F0FFF
 
    Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess As Integer, ByVal bInheritHandle As Integer, ByVal dwProcessId As Integer) As Integer
    Private Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As Integer, ByVal lpProcName As String) As Integer
    Private Declare Function GetModuleHandle Lib "kernel32" Alias "GetModuleHandleA" (ByVal lpModuleName As String) As Integer
    Private Declare Function VirtualAllocEx Lib "kernel32" (ByVal hProcess As Integer, ByVal lpAddress As Integer, ByVal dwSize As Integer, ByVal flAllocationType As Integer, ByVal flProtect As Integer) As Integer
    Private Declare Function WriteProcessMemory Lib "kernel32" (ByVal hProcess As Integer, ByVal lpBaseAddress As Object, ByVal lpBuffer As Object, ByVal nSize As Integer, ByVal lpNumberOfBytesWritten As Integer) As Integer
    Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Integer) As Integer
    Private Declare Function CreateRemoteThread Lib "kernel32" (ByVal hProcess As Integer, ByVal lpThreadAttributes As Integer, ByVal dwStackSize As Integer, ByVal lpStartAddress As Integer, ByVal lpParameter As Object, ByVal dwCreationFlags As Integer, ByVal lpThreadId As Integer) As Integer
    Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal hHandle As Integer, ByVal dwMilliseconds As Integer) As Integer
 
    Public Function InyectDLL(ByVal Dll As String, ByVal PID As Integer) As Boolean
        On Error GoTo 0
 
        Dim Buffer1 As Integer, _
         Buffer2 As Integer, _
         OpenedP As Integer = OpenProcess(PROCESS_ALL_ACCESS, False, PID), _
         AddressP As Integer = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryW"), _
         rems As Integer = VirtualAllocEx(OpenedP, 0, Len(Dll), MEM_COMMIT, PAGE_READWRITE)
 
        WriteProcessMemory(OpenedP, rems, Dll, Len(Dll), Buffer2)
 
        CreateRemoteThread(OpenedP, 0, 0, AddressP, rems, 0, Buffer1)
        WaitForSingleObject(rems, &HFFFFFF)
 
        CloseHandle(OpenedP) : CloseHandle(rems)
        Return True
 
    End Function

Yo he hecho esto siempre así y siempre ha funcionado ._. uso Microsoft Visual Basic 2008 Exprres Edition
Tambien cabe destacar que esto siempre me ha confundido siempre dicen que asi no se declara y no entiendo porque ya que siempre me ha funcionado.

pd: Yo aún no estudio esto me falta 1 año para entrar a la universidad.