For step b, I've just installed Internet Explorer instead of updating the registry.
If you install Elster Formular like you can even transmit the form. Somehow the application window isnt shown at the taskbar so Im using ALT+TAB. The inline help also doesnt work, as mentioned before. This is because Wine doesnt support chm and I couldnt find a way for adding it.
That's it. ElsterFormular installs without MDAC and JET, but there are some things you cannot do without it (like transmitting the form).
Oh, the help subsystem does not work (it's based on .chm - no idea about that)