The extra chapters will give you a good idea what is involved, and what prerequisite knowledge is assumed. That is, Swing GUI, RMI/Sockets, I/O and optionally with NIO. You will have to know your SJCP threading and be able to strictly program to a style guide. This
SCJD is no "piece-of-cake" like
SCJP.
A useful book to read is
this one. It does not tell you exactly how to develop the assignment but gives stong pointers and coding examples. You will have to read a lot of API docs too.
There is no specific 1.2 or 1.4 SCJD but from this April on new candidates have been getting a different set of assignments (no code is provided, except for an interface with no implementation).
If you have little or no programming experience it will be very tough, maybe a better start would be to do the CattleDrive (with the nitpicking package) here on JavaRanch. It certainly helps to give you the required developer's "mindset".
-Barry