The cookbook is too "heavy". If you cover what's in the "XML Nutshell" and look at some examples on the web, you should be able to cover the XSLT code questions (I got about 5 on the test).
The best way to figure out is to take the trial exam ($10). It is close to the real one in most areas.
Actually, I already took the $10 sample test and score something like a 45%-ish score with whatever XML knowledge I had from experience. Maybe I'll start with the Nutshell book and see how it goes...