While it isn't a compendium as far as in-game structure goes, you can still build a game system rule set out of handouts. That allows players to look up things and copy/paste whatever info might be needed to their character sheets. Since it is easy to create links from one handout to another, you can also archive most of your handouts to keep them from cluttering up the journal too much. If your friend does that, then the first thing to build would be a "base game". You don't run games there, you just build up your default game rule set, and then copy that game any time you want to run something.
