The Joderhorn is well frequented via it's normal route on the WNW Ridge. The SE Ridge is less frequented and I think therefore, although he's significantly harder to climb, a better way to climb the mountain. It can be climbed in a day starting early in the morning at Mattmark. The SE Ridge is a good introduction for alpine rock climbing in it's grade.
The climb is described well in Valais Alps East
Selected Climbs by Swindin and Fleming.
From the Monte Moro Pass, head SE untill you reach the end of a ski lift rising from the Italian side. Walk trough the coll by the lift and descend into a stony boulderfield on the other side. When there's no snow, traces of a track should be visible. Continu below the S Face of the mountain and finally climb to an obvious saddle in the SE Ridge. Note that this is not the Staffa Saddle between Joderhorn and Battel, but a minor saddle, already 50 to 70 meters higher on the SE Ridge. It can be reached by scrambling up some easy rocks and plates (I-II). There's an iron pole standing on the minor saddle.
From the saddle traverse a few meters left into the face. The start of the climb is marked with a piton. Climb a little overhanging corner (III+) and continu in the same direction to a ledge with a belay. From here climb a diedre and a steep chimney/crack (IV) to a niche with a belay. Attention, you can easily get jammed in the chimney after the diedre when carrying a backpack...
From the belay, continu, easily this time, in the same crack and pass the next step on the left side. On the top of this step you'll find a piton. From here, climb the next 10 meter high step, which is easy, to the base of an almost vertical wall split by a crack. Climb the wall (IV).
At this point the level of the ridge eases, continu on the crest, pass a corner with a pull up and then up the ridge to another wall. It is possible to climb this (III) in the direction of a square gendarm, but it is easier to pass it on the left side by traversing a bit into the face and climbing back on to the crest just below the gendarm, which then has to be passed on the right side. Now scramble straight to the summit which isn't far away.
Descend on the normal route (WNW Ridge - F)
Early in the season (end of June, beginning of July), it is recommended to use crampons and ice axe for the approach (and later descend). But in normal circumstances it is possible to pass a few little snowfields and reach the beginning of the climb without crampons or ice axe. On the ridge they're not necessary. Of course it's recommended to use a double rope (2x50m). Carry a rack of nuts, friends and slings for protection. Don't forget your helmet as it is a rock climb. Carry a compass with you (in fact you should always have it with you in the mountains). The area often gets covered in thick fog coming from Italy already during the morning.