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While it's technically possible...it's easier to accept defeat and find an alternative solution. Why do you need to run VBA under PHP?
Is the server Windows powered? Then you could maybe write an extension wrapper around the VBA DLL's and pass VB code to the PHP extension function for execution. Any VBA interpretor would work but that is a massive complex task for anyone, nevermind someone who is asking how this would be done.
PHP can connect to Excel using COM, so you should be able to use that. You'll need to be using a Windows server, and it'll need to have Excel installed on it (or maybe just Excel Viewer..). Unfortunately it's the sort of thing that noone ever really does because most people who need this sort of functionality build their websites in .NET, so I imagine you'll need to work out exactly how to do on your own.