I just switched to mac not too long ago and I've been looking a way to copy,cut, paste, undo and redo with the alt key instead of typing funny letters. I've been searching for a couple hours now and nothing.
I was able to define these shortcuts in system preferences in mac osx, but it still types the letters and doesn't issue the commands.
I tried entering the commands in rubymine's keymap editor but i ran into some problems. First, it would only let me define certain keymaps with the alt key, like alt-c, but wouldn't let me define alt-v and alt-x. So i found the "/Library/Rubymine32/keymaps/Default for mac os x copy.xml" file and manually edited, with limited success, the keyboard shortcuts still don't send the commands.
However, i did find a workaround that i think will be good. I just set control to do move caret by word and set the cut copy and paste to use control as well and this should work.