Risolto. Per chi dovesse avere il mio stesso problema:
definire una public function in vba
codice:
Function FindAndReplace(ByVal strInString As String, _
strFindString As String, _
strReplaceString As String) As String
Dim intPtr As Integer
If Len(strFindString) > 0 Then 'catch if try to find empty string
Do
intPtr = InStr(strInString, strFindString)
If intPtr > 0 Then
FindAndReplace = FindAndReplace & left(strInString, intPtr - 1) & _
strReplaceString
strInString = Mid(strInString, intPtr + Len(strFindString))
End If
Loop While intPtr > 0
End If
FindAndReplace = FindAndReplace & strInString
End Function