Thanks for your help
I have finaly found my way...
Here it is

On Error Resume Next
Set appXL = CreateObject("Excel.Application")
If Err = 0 Then
addin_folder = appXL.UserLibraryPath
Else
addin_folder = _
WshShell.ExpandEnvironmentStrings ("%APPDATA%"&"\Microsoft\AddIns\")
End If
On Error Goto 0
Set appXL = Nothing

Regards
Alain