Implantation of a cardiac stimulus system using the ITV. Superior, intercostal, and inferior access methods are discussed and disclosed. Superior access may be performed using the brachiocephalic vein to access the ITV, with access to the brachiocephalic vein achieved using subclavian vein, using standard visualization techniques. A positioning mechanism may be advanced to the ITV, a location of the positioning mechanism may then be obtained, and an external access may then be established. Inferior external access may be accomplished inferior to the lower rib margin via the superior epigastric or musculophrenic vein. Intercostal external access may be accomplished via an intercostal vein between two ribs. A lead may then be attached to the positioning mechanism and drawn into the ITV.