I normally type in a special font for dyslexics, Dyslexie. I can go to character map and snag Greek letters and other symbols, like those used in math, but it is a royal pain while typing.
?
For serious writing, I place {} around the normal ASCII English letter and then I'll go back and replace them after I finish, in TV we called it "We'll fix it in post."
?
I find trying to engage number lock and press alt while trying to remember what key to press for what Greek letter I want to be a bit too confusing, of course I could make a cheat sheet, that I'd have to keep track of.