A tool (1) for subcutaneously implanting a subcutaneous electrode comprising several wire patch electrode segments by way of a single surgical incision. The tunneling tool (1) comprises a stylet (2) and a peel-away sheath (8). The tunneling tool (1) is inserted into an incision, in a direction which corresponds to the desired placement of an electrode segment. Once the tunneling tool reaches a desired position, the stylet (2) is withdrawn, thereby revealing the interior of the peel-away sheath (8) and a resulting subcutaneous tunnel. The corresponding electrode segment is then inserted into this subcutaneous tunnel, and subsequently implanted in the patient. The implantation procedure is then repeated as many times as is necessary, using the same incision, until all the electrode segments for the particular electrode configuration have been implanted.; In addition, the tunneling tool (1) can be adapted to conform to varying electrode segment sizes, which thereby allows the tool to conform to the varying needs of each individual patient. As an even further feature, the tunneling tool (1) can be constructed in a curved configuration to facilitate electrode implantation in the lateral thoracic region of the body.