I've updated the instructions with a draft schematic. I'm still learning Kicad and haven't figured out how to export the schematic as an image so it's just a screenshot for now. Depending on where you bought the audio jacks the pin numbers for the jacks might not match the pins on the schematic so keep an eye out for that.
I'm back from vacation and I'll start updating the page with step-by-step instructions. If there's anything I can add that would make it easier to understand let me know.