I've seen lots of ideas on this page on how to remove the key beeper and seatbelt beeper etc by performing wiring mods. I went right to the source of the problem and removed the damn piezo buzzer itself, took no longer than 5 mins start to finish. The piezo is on the circuit board on the back of the instrument cluster (speedo/tacho etc). With the cluster removed, you just remove the back cover to expose the circuit board, the piezo buzzer is easy to spot, about a dozen twists left/right and it popped right off, the two pins cleanly snapped off flush with the circuit board, (I could of de-soldered the piezo from the other side of the circuit board but you have to remove all the instrument needles to do this which I was not to keen on doing).
No more annoying beeping, ever!
I cannot seem to get my pictures to show on this post, copy and paste the below link for pictures