Sorry, didn't catch that in your orig post. Have you tried saving it as an xlsb (Binary Workbook) file or ,depending on what your code does, as an xlam (Add-In)? Here is the vbs script to add a trusted location to an office program

    Dim WshWhell
Set WshShell = CreateObject("WScript.Shell")

'Acceptable Office Version Values: 2003 = 11.0, 2007=12.0, 2010=14.0
    'Acceptable Program Values: Excel,Access, Outlook, PowerPoint, Word, Visio.
    'There is a "Common" program group that may possibly be used but I haven't tried it yet.
	'The location ID is a unique value such as "LOCATION99"

RegEdPath= "HKEY\_CURRENT\_USER\\SOFTWARE\\MICROSOFT\\OFFICE\\(Office Version)\\(Program)\\SECURITY\\TRUSTED LOCATIONS\\(LocationID)\\"

WshShell.RegWrite  RegEdPath  , ""
	WshShell.RegWrite  RegEdPath & "PATH" , "C:\\MyTrustedPath"
	WshShell.RegWrite  RegEdPath & "Description" , "Description"		
	WshShell.RegWrite  RegEdPath & "AllowsubFolder" , 1 , "REG\_DWORD"

Have you tried converting the spreadsheet to 2007? It would require security changes but it may just work. I have a vbs script that adds trusted locations via the registry if you need.

Do you know if any of the Korean users can add a module manually?