Being a newbie, I
Sorry, I thought you meant to programming in general.
If you're happy to use the analogue comparator IPs...NOTE: I spent some time on this then realised it won't work because the quescient state is the same as the interrupt state ie AIN0 > AIN1 but it's late and I'm too tired to think about it any more so I'll post it anyway in the hope it might give you a start.
In the quescient state ADCn and AIN0 at the same voltage level and AIN1 is 0.6v lower.
When a button is pressed ADCn goes immediately to Xv, AIN1 goes immediately to Xv - .6.
After a short time (and when the switch has stopped bouncing) AIN0 reaches Xv which is higher than the X - .6 on AIN1 which causes a comparator interrupt and the ISR reads ADCn etc etc.
May need a resistor from AIN1 to GND to get some current flowing through the diode.
No thought put into what happens when the button is released.