The present invention relates to methodology of and apparatus for accurately positioning devices for performing endoscopic cannulation, papillotomy and sphincterotomy and similar procedures. The sphincterotome with a steerable or adjustable distal segment of the present invention allows the physician to control the position of the distal tip of the device independently of the endoscope and adjust for inconsistencies in the device and the anatomy. According to one embodiment of the present invention, a threaded portion of a cable assembly cooperates with a torque transmission element and a cog to enable the operator to rotate a cutting wire into a desired position relative to the catheter. Alternate embodiments allow the operator to fix the depth of a needle knife while allowing, if desired, accurate rotational positioning of the associated catheter. Threaded stabilizing elements, pivot elements and a steering wire may be used together or individually to accomplish these features. Presently available products that may be modified according to the present invention include, but are not limited to, Boston Scientific Sphincterotomes and Needle Knives.