A hydraulic jetting assembly is provided herein. The jetting assembly includes a jetting hose, with a jetting nozzle at its distal end. The jetting nozzle comprises a tubular stator body having a fluid discharge slot, and a tubular rotor body residing within a bore of the stator body. The jetting nozzle has one or more bearings residing between the stator body and the surrounding rotor body to accommodate relative rotational movement. The jetting nozzle includes a proximal end configured to sealingly connect to an end of a jetting hose, and to receive a high pressure jetting fluid. Preferably, the nozzle has an outer diameter that is equivalent to or slightly larger than an outer diameter of the jetting hose. Preferably, the jetting assembly has at least three actuator wires configured to induce a controlled bending moment at its distal end, thereby providing for a steerable downhole tool. Jetting collars may be placed along the jetting hose to overcome drag force.