i'd like to sue interrupts
It seems in the U.S.A. you can try and sue anything.
In machine code you just need to set the interrupt vector to the address of the ISR function, something I can't see your code doing. But in C it is a bit more complex than this as internal registers need to be saved and restored.
for various reasons i'd like to
sueuse interrupts without using the "attachInterrupt" function.
Can you name just one please? I am sure it will not be valid.