From reading what Marian Carr Knox said
here and
here, it is obvious that the disputed documents are based on actual documents typed by Mrs. Knox and that whoever wrote them must have had a copy of what she typed. If that person had been a Democrat wanting to discredit George W. Bush he/she could have just used copies of the official documents instead of going through the elaborate process of creating new ones to pass on to Bill Burkett, as discussed
here. And if we were in a court of law (or a country where the media really cared about the truth) we would just enter the testimony of Mrs. Knox into the record in lieu of the actual documents.
I think Bill Burkett was set up by someone but the details are still sketchy. The key to all this is the phone records that he says will confirm he received calls from the mysterious "Lucy Ramirez." If he did really receive calls and is not delusional (a possibility that must be considered) then there is a trail to trace. USA Today and CBS have so far not been able to find any sign of Lucy Ramirez but that doesn't mean she doesn't exist. If Roger Stone is behind the documents then whomever was playing the part of Lucy Ramirez could be one of his known associates.
If the documents were a dirty tricks plant job we will probably know it sooner rather than later.