If you just want to run a curses app embedded in a Tk window, you should be able to do it by embedding an xterm with the -e option, to execute the curses app. That should take care of all the keys working in the curses app. See embedding xterm into a Tk app. In that script, if you change it to

system("xterm -into $xtId -e /usr/bin/mc &");
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It will run midnight commander in the Tk window.

If you are trying to mix Tk and Curses code, in the same window, it will be a tough thing to do. Actually it would be easier to define what the curses application is doing, then port it to Tk code.