Time-travel technology? Why not just use the kind of digging equipment that traitionally gets used to make canals?
OK, technologically this is quite an engineering challenge, but I suspect if they had wanted to, they could have - though probably not in the 50s, when they had better things to do with their scarce resources. My school atlas identifies the watershed at 240 metres at Jebel Mubrak. If you are just interested in getting the water in, drilling a tunnel is probably easier, but if ypou want to build an actual navigable canal, this will take major efforts.
Now, the legal and political headaches connected with this - oy vey. Fiorst, the bottom of Wadi al-Araba is the Israeli-Jordanian border, which means you are going to end up flooding Jordanian as well as Israeli territory and creating a boundary along an artificial waterway of major strategic importance and saddled with considerable maintenance costs - not a good idea to say the least. Then you have to realise that the area arouind the dead sea and a goodly bit of the Jordan Valley are below sea level, which means you are going to flood a couple hundred square kilometres of land, some of it among Israel's and Jordan's most fertile. Jordan is probably going to be more concerned, given Israel has the coastal slopes with the Mediterranean rains. Then you are also going to affect a largish part of the West Bank, so even post-occupation it's going to be a legal nightmare to figure it out.
I'm not sure the added rainfall and new port facilities will compensate for that.