The starting point is from Arenal valley camp, often referred to as ODS BC. Information how to get there on main page on the Getting There section. Head up the main valley towards the foothills of the mountain. Follow the main (small) river to the left of the first rounded hill and continue upwards on the all the time gradually steeper and fainter path. When coming around a sharp bend you´ll see glaciers on the right hand side of the river valley. Scramble towards them until you´re at the a flattish place where you can camp if need be. This is where the climb start for real.
To go for the Mike Dorse Direct, if I got it right, you have to head for the steepest glacier furthest away from the trail and the flat area. There are three glaciers and the first is a 40-45 degree, the middle one is probably a 45 degree + and the third one is up to 55 degrees at the steepest sections, but then you really have to look for the steepest possible line. The figures given above is the steepest sections. To get the average you can probably subtract about 10-15 degrees on the above figures. If you for some reason want to quit the ice climbing, there are alternative ways up towards the ridge above you. The most obvious and easiest is the normal route on the rocks on your right hand side. I could not find any indications of crevasses and the ice was a mix of everything from blue solid ice to crusty snow.
When you´ve climbed the 400 vertical meters of snow and glaciers, you arrive at a much flatter section. Walk towards Ojos and keep to your left under the ridge. The normal route follows the ridge to the summit and there is a way to get to the Chilean normal route as well if you head over the ridge at an early stage. There are probably many different variations of this route, but I followed an almost straight line towards a point very close to the summit. The last 80-100 vertical meters are a nervous semi-technical climb with lots of rotten and loose rock. You´ll arrive a couple of meters to the right of the eastern summit pyramid, from where you have to climb down some meters to the gap in between the two peaks. Climb up to the half-a-meter higher western peak if you feel like bagging them both. There are lots of fixed ropes hanging from both peaks and they were all of very doubtful quality.
Crampons, an iceaxe, walking poles are great to bring. Depending on your skills, it may be of help to bring some rock climbing gear, a harness, a 30 meter 7-8mm rope, rapelling device and slings. The whole route can be done with only crampons, but then you´re taking risks on the rock climbing sections close to the summit. For those who don´t feel confident with climbing the above mentioned gradients of snow/ice should bring snowstakes and some screws.
I was concerned about reaching the summit as fast as possible as I attacked the mountain from far away and a strong wind was doing its best to blow me off the peak. I was trying to go towards the summit very direct and to be a bit sheltered from the wind. That was why I followed the route mentioned above. I had no clue if it was climbed before and if it had been, by whom. When returning to Fiambalá and Jonson Reynoso´s office I explained how I had climbed ODS and that was when I got to know it is called Mike Dorse Direct. It's fair to presume it's the same Canadian Mike Dorse who made a north ridge attempt on K2.