Ive seen many solutions online but none does exactly what I want. What is the best/simplest way to get any keys pressed in a given process (not my console applicaton) while
Oh, so you're looking for "Autofire" in old-school gaming terms?
Instead of writing your own keyboard hook app (unless you're doing it for fun/the thrill of it/the exercise) you might want to look at AutoIt or AutoHotkey, which are both pretty good for keyboard/mouse automation.
See this thread for instance... http://www.autohotkey.com/board/topic/40598-autofire-keyboard/