Pythos and rulle34: I updated the Start career with XVIII thread with instructions how to enable the XVIII for the 1943, 1944 and 1945 career.
http://www.subsim.com/radioroom/showthread.php?t=132224
hyperion2206: Use Skwasjer's S3D program to edit SIM files. Editing the H2O2 is quite easy with this program.
http://www.subsim.com/radioroom/showthread.php?t=119571
I actually posted somwhat detailed instructions somewhere around here how to edit the H2O2 but I can't find them.
edit: found them.
http://www.subsim.com/radioroom/showthread.php?t=132516