Ok then, I'll go ahead and get that digital pot from SparkFun, that should be a simpler solution, right? Basically it does the exact same thing that a physical potentiometer does, but can be controlled via digital signals, meaning that I could use the Arduino to set the pot to a specific value between 0 and 1.5V and it would be a real analog signal? The whole reason I'm doing this is because I want very fine control of the sticks, particularly the rotation (right stick/triggers). For my application, I need there to be no chance of bumping the left stick (movement) at all, else I waste a lot of time and have to redo everything. Before I was simply holding the controller and keeping my fingers as far away from the right stick and triggers as possible, but my hand starts to cramp holding the controller like that, so I want to be able to control it from the computer. Plus, writing some macros would be nice.
At any rate, that digital pot you linked would be the way to go?
Edit: From what I've read, the pots in the controller are linear 10k, but I used a multimeter, set to the 20k setting, to test the resistance between the two outer leads and I got a reading of 1.5 (which I assume means 1.5k, since the meter was set to the 20k setting). I tested between the right and middle leads, then the left and middle leads and got a reading of 4.1k then tested the left and middle leads and got 3.3k. That doesn't make any sense to me. I'm 100% positive I wasn't pushing the sticks at all, I had the thing clipped in my helping hands tool.
Edit 2: Since I don't really know anything about digital pots, could you point me in the direction of a really good, high resolution one. Looks like the SparkFun one you linked to only has 129 steps, which might not be enough to accomplish that fine control that I need. Like I said, I really know very little about these things, so any help I can get will be useful.