Excel 2011 / Mac / Can't find project or library

Dear,

I recently moved to Mac (using Excel 2011), and now find myself unable of running a macro that worked on Windows (Excel 2007). The problem: RegExp is not found, I get "Can't find project or library" on it. The Tools > References item where I could potentially add reference to VBScript Regexp 5.5 or something similar) is *NOT* available...
Any suggestions?

The code:

Dim newSheetName As String
Dim reg As RegExp
newSheetName = ActiveSheet.Name
reg.IgnoreCase = True
reg.MultiLine = False
reg.Pattern = "runti.*$"
newSheetName = reg.Replace(newSheetName, "rt")

Kind regards,
Chris