I made a two-piece into a three piece one time, but that was by accident. Actually, I've heard this question asked before and if I remember correctly, the ferrells (or lack of them) is what presents the greatest problems. You might have better luck asking this question over on Rodbuilding.org http://www.rodbuilding.org/list.php?2 where there are hundreds of very talented rod builders that are always willing to share their knowledge. Good luck and let us know what you find out.

Jim Smith