This is too cool! I was looking for a diagram someone posted years ago (couldn't find it - sorry) and I came across a model company selling add-on stuff for Revell's 1/72-scale U-boat. If you scroll down the list you'll find detail sets for German crew reloading torpedoes! Click on their links and you'll see pictures!
http://www.michtoy.com/MTSCnewSite/p...h_masters.html