You might check with the education department at a teaching hospital. Not all hospitals do them. The hospital were I was has an open 'shadow program' where students and practicing nurses alike, can visit (almost) any area of interest in the hospital... whether it be areas of potential job interest that they'd like to check out, or areas to enhance their education.
I had not requested to watch an autopsy that day. I was actually shadowing the IV/ PICC team - but they got caught up and I had time left to spare, and the opportunity arose so I took it.
3 years ago, a dear friend of mine lost her husband suddenly, and he was autopsied at the same hospital where I saw this one. I kept thinking of him, my friend, and their child...and how I was waiting with her for the reason why he died too soon, and remembered during that wait how I fought to avoid the images of autopsy that were in my mind, and how I hoped she wasn't having them too.
No, I hadn't planned on seeing an autopsy that day... but I did, and I think it made me a better nurse, so it happened for a reason.