So, after doing some more research, I'm pretty sure there's no way to do this.
Fortunately, for most parts of the game (read: using special attacks in combat), the QTE's/Timing events are either fairly easy, or fairly inconsequential. The game just isn't hard enough that blocking every attack is the difference between winning and losing, and the difficulty slider is there if you really do have trouble.
Which leaves QTE's like the one that you're confronted with during the aforementioned night one Alien Abduction sequence. For which, at least for me, there was only solution which I could make work, after several hours of trying (and, I think, possibly damage to one of my two gamepads - something is seriously mistuned, and I suspect it is at least partly a bug, based on the lack of complaints about the issue at the level of severity I'm describing from console players). Either way, I settled on a solution because it worked, and because this is a single player game, and because my pride was already completely demolished. I cheated.
Specifically, I used Autohotkey and created a script that mashes the button required a dozen times instantly. I hit the macro once, and it passed the QTE check. You can literally follow the steps from the AHK Tutorial, and simply, instead of typing in
#space::Run www.google.com on the blank line, simply paste in
Then, whenever you press Control+alt+s, it'll act as though you've mashed the button. (S is the games keyboard equivalent to 'a' on the gamepad for these QTE's. Should you need a different button, just replace the s's with d's or a's or whatever.
Note: To use this macro, you'll need to unplug your gamepad momentarily so that the game reverts to keyboard controls, but the game switches between control schemes very gracefully and on the fly, so there should be no need to worry about restarting it or other hoops to jump through that might make this solution inconvenient.
This won't help with precision based QTE's, but for the truly egregious button mashers, this should solve the problem.