Hey Ron....
I suspect it would be easier to start with a chunk of steel than do a retrofit....... I love the look and feel of stacked leather but from a practical stand point a full tang and Micarta make a much better combo...... Not, mind, that the standard Zytel is not a better alternative than leather....... It may not be pretty but, it works........BTW Leather sucks up moisture and when it dries it shrinks and eventually if the knife gets a lot of use the washers get loose....... Leather sure is pretty though..... If you are after pretty think about a stabilized wood.......
All Best....
Ethan