Source control of Excel VBA code modules

I'd like to be able to source control my Excel spreadsheet's VBA modules (currently using Excel 2003 SP3) so that I can share and manage the code used by a bunch of different spreadsheets - and therefore I'd like to re-load them from files when the spreadsheet is opened.

I've got a module called Loader.bas, that I use to do most of the donkey work (loading and unloading any other modules that are required) - and I'd like to be able to load it up from a file as soon as the spreadsheet is opened.

I've attached the following code to the Workbook_Open event (in the ThisWorkbook class).

Private Sub Workbook_Open()
    Call RemoveLoader
    Call LoadLoader
End Sub

Where RemoveLoader (also within the ThisWorkbook class) contains the following code:

Private Sub RemoveLoader()
    Dim y As Integer
    Dim OldModules, NumModules As Integer
    Dim CompName As String

    With ThisWorkbook.VBProject
        NumModules = ThisWorkbook.VBProject.VBComponents.Count
        y = 1
        While y <= NumModules
            If .VBComponents.Item(y).Type = 1 Then
                CompName = .VBComponents.Item(y).Name
                If VBA.Strings.InStr(CompName, "Loader") > 0 Then
                    OldModules = ThisWorkbook.VBProject.VBComponents.Count
                    .VBComponents.Remove .VBComponents(CompName)
                    NumModules = ThisWorkbook.VBProject.VBComponents.Count
                    If OldModules - NumModules = 1 Then
                        y = 1
                    Else
                        MsgBox ("Failed to remove " & CompName & " module from VBA project")
                    End If
                End If
            End If
            y = y + 1
        Wend
    End With
End Sub

Which is probably a bit overcomplicated and slightly crude - but I'm trying everything I can find to get it to load the external module!

Often, when I open the spreads