Now i'm doing some kind of translator (to C), that can turn second to its functional equivalent -- first:

void handle_mcucsr(void) __attribute__((section(".init3"))) __attribute__((naked));
void handle_mcucsr(void)
{
    mcucsr = MCUCSR;
    MCUCSR = 0;
}

handle_mcucsr: sect[ion] .init3, naked!
	mcucsr = MCUCSR
	MCUCSR = 0