Ok I just wrote this code for you. Add it into sensors.c. It'll be included in all future Axon code versions. Let me know how well it works for you!
//Sharp GP2Y0A21YK IR Range Sensor - 4 cm to 30 cm
int sharp_IR_interpret_GP2Y0A21YK(int value)
{
return 739.38*pow(value,-.8105);
}