Cerro Perito Moreno is an Andean mountain overlooking the town of El Bolson in the province Rio Negro, Lake District, Argentina. The mountain has a ski area on its lower slopes that operates in winter. The summit is a large rocky crag on a ridge surrounded by small glaciers. There is no trail towards the summit and it is a sketchy scramble (class 3 at least) on the easiest route. It affords views West into the Chilean Andes and East over the El Bolson valley.
From San Carlos de Bariloche, the main town in the Argentinian Lake District which you can fly into from Buenos Aires, get a bus ticket south to El Bolson. This is a several hour drive so you need to use the main bus station East of town. From downtown El Bolson take a local bus towards Mallin Ahogado, all the way to the end of the route. It will drop you on the dirt road (where/how far depends on the day of the week) that heads towards the ski area. The walk to the bottom of the ski hill can be up to 15km depending on where the bus drops you.
There is no red tape. The local club Andino, can provide you with directions but will advise against summiting. There is no trail towards the summit once you reach the far side of the high plateau above the ski area.
With the right bus towards the ski area this summit should be doable in a day. However, there are no restrictions on camping should you need to. There are also Refugios operated by the local Club Andino on the Rio Azul, which allows you to sleep close to the mountain and arrive at the bottom of the ski hill by a walking trail from the other direction as the dirt road.
Easiest Route (class 3, grade I)
From the Bottom of the ski hill hike straight up. In summer the access road provides decent switch backs. Shortly after you pass the end of the ski lifts you will come up on a barren high plateau. From here the summit is visible ahead and to your right (WNW). Head across the plateau, following the trail in summer, until you reach the base of the rock ridge. A sign points the trail south (left) from here to a view point over Rio Azul, but an alternate trail leads north (right) along the ridge until you can climb on to the glacier. Traverse the glacier to a small rock ridge that protrudes from it on the right hand side. You can use this ridge to climb without any technical gear (even without crampons and ice axe although this is somewhat dangerous) to the upper reaches of the glacier and from there up to the schrund and the base of the summit rock. Climb up the loose rock slope to the col on the ridge behind the summit, above the highest part of the glacier. From here you can scramble up the last of the rock pinnacle to the summit. On the descent you can Glissade the glacier without worry as it has no crevasses on this section and levels off substantially before ending over the valley, making stopping very easy.
Other routes I have not climbed but they appear much more technical and difficult, especially from the North and East.