Go to the shoe care thread there is a ton on this probably 5 pages from the end of the thread...seems a combo of vinegar and distilled water helps get the oil out.. Scrubbing will just do what you discovered and remove the finish as Bourbon is a finish not tanned that way.
Anyway try the vinegar remedy...
Thanks -- just tried them over there. Any way to restore the Bourbon finish?
From what I understand that is a burnish they do to create the Bourbon effect so I am not sure but If I were to do it would probably us some black wax polish and apply it in a very blotchy manner and brush and keep doing that with very thin layers