Atmega collecting and relaying interrupt calls
The interrupt vector table is provided by the C runtime. It is
not normally intended to be overridden by user code. You can, however,
do it, if you replace the whole C run time by your own, and compile your
sketch with the -nostartfiles option.

I have played this game once I was trying to accurately assess interrupt
latencies. See the details in this answer (the answer is long,
but you can go right to the last section).