Hi WTint,
Your question is commonly asked and I think the reason is because in
SCJP, we have many resources and books sorted according to Sun test objectives. There, it is really important to guide the preparation for the
Java exam.
As XML test includes many vague and not self contained topics, I dont think it is a good idea to go after documents closed to test objectives. Also, as far as I know, there is no XML book designed for IBM certification test.
I think many certified people got aroud many documents to master XML test objectives.
Follow those links and good luck,
Adrian