Auto-Resetting jQuery Countdown Timer To Tuesday and Friday

I need a simple jQuery countdown timer which counts down to Tuesday, then resets to Friday, then Tuesday, then Friday, etc. It should countdown to Tuesday and Friday every week, forever. As soon as it hits zero, it should automatically start counting down to the next day in the cycle (either Tuesday, or Friday). The script should be easily understandable so I can alter the dates, for example I may want to change it to Wednesday and Sunday. I should be able to easily modify the script without doing any heavy coding.