how would I create a string with the <alt>-<enter> key combiniation in the middle of it which I can then write out to a file? Would it be as simple as outputing the unicode characters for <alt> and then <enter>?
There's no such thing as a character for alt or enter. They're sometimes called meta-keys, and what an application does when they are pressed is up to the application. Usually enter creates a line break, but even then, the characters that make up a line break are platform dependent.
Explain what you are trying to accomplish, and we can probably suggest a better way to do it.