Ok, after some googling of the U-Bootkommandanten Handbuch, I was able to find out that the first 100 or so pages have been transcribed on to the 9th flottilla website (a german SH3 flottilla).
http://www.9teuflottille.de
The handbook has been transcribed into the section accessed by the "Wissen" tab at the top of the index page.
For non german speakers, you could try using a web-based translator on it, though it will probably turn out a bit dodgy as always.