Start from the Argentiere Hut (see the main page for details.)
(See the two climbing guides in the book section for further information. This description comes mainly from the Rebuffat book.)
DO NOT ATTEMPT THIS ROUTE LATE IN THE SEASON AS THE COULOIR IS DANGEROUS DUE TO FALLING ROCKS.
From the Argentiere hut (2771m) take the path which follows the water pipe, then the morraine of the Amethystes Glacier and skirt the foot of the Arrete du Jardin passing directly below the Y-couloir of the Arrete de Fleche Rousse, then traverse right towards the couloir below the Col Superieur. climb this to gain the col (3690m) - 2.5 to 3 hrs.
Climb the north ridge of the Tour Noir on mixed ground rather than taking to the shattered and unstable rock of the West side. Keep as close as possible to the more impressive but easier crest of the ridge to reach the summit. (3.5 to 4hrs from the summit).
Descent. This follows the ordinary route and the Javelle Ledges on the SE Flank. Reach the col between the two summits, and on the Swiss side descend the spur right on big easy blocks. when it steepens traverse right towards the Javelle Ledges. To get to the ledges you will have to descend a clabby chimney (maybe abseil?). The Javelle Ledges are quite nerve racking: do not descend too far or you hit scree. Reach the ridge and descend it on the French side to the Col d'Argentiere. Descend the glacier to the hut. (Watch out for cravasses late in the afternoon.)
Slings, rope and harness. No real need for much rock climbing hardware. Cravasse rescue kit - and the knowledge of how to use it!