Check whether syntaxhighlighter recognises VBScript; this is more likely than a specific mention of VBA and almost identical for highlighting purposes. (Just checked, it mentions Visual Basic and VB.NET, so you can continue with syntaxhighlighter - which seems sensible.)
highlight.js mentions VBScript, and has an example, but I haven't used it myself.
In fact, I think most syntax-highlighters will show a reasonable representation of VBA code.