It is possible to use the ATmega8 interrupts in Arduino. You should be able to use the standard syntax documented at: avr-libc: <avr/interrupt.h>: Interrupts
Note that the timers are already used by Arduino: timer 0 increments the time count returned by millis(), timer 1 and timer 2 are used to generate the PWM outputs on pins 9, 10 and 11.