If you haven't got the Microsoft Script Control, download it from somewhere in http://msdn.microsoft.com/scripting [microsoft.com]. 
Then in Excel, set Tools - References - Microsoft Script Control. 

In your code, you can now eval and execute Perl code, and use it in any Functions that you've declared as public - here's a trivial example:

Option Explicit
Private sc As New ScriptControl

Public Function uc(txt As String) As String
    sc.Language = "PerlScript"
    uc = sc.Eval("uc(" & txt & ")")
End Function 
Now you can type =uc("hello") in your spreadsheet to call the above function. 
You can even use modules; I had an example using Lingua::EN::Numbers, but I can't lay my hands on it at the moment. 

Hope this helps.