i would strongly recommend against it. See my experience above connect ET to TK with 1hr 20 min. ET is pretty bad with interfacing with other airlines. They may be part of Star, but their systems are not connected and the general attitude is not helpful. The kind of "going above and beyond" attitude i'm seeing here from RJ does not exist with ET. I don't have any experience with MS, but they don't inspire confidence in me either.
For practicalities, i refer you to my report above as well. Departures and arrivals are two separate buildings and you need to wait for a van to take you from one to another. The airport is not setup for transfers well.
the only chance you have of making the connection is if MS gives you a boarding pass, which sounds like it can't be done remotely. I wouldn't rely on ET to check you in, print a pass and bring it to you airside.