Am in the very-very early stages of preparing to seek registration to QS-9000. I am currently a ASQ CQA, and am planning to train internal auditors using the Wortman book (QCI). Any thoughts on the acceptability of this from registrars?

Write your training requirements to match what you plan to do. I don't see a problem.

From a registrar perspective: Document the minimum qualifications your company or your customer requires. It's best to mention all acceptable alternatives to meet minimum qualifications to allow you some flexibility. Example, if the QCI course is going to be a two day course, you don't have to state QCI or Wortman...just document two days on-site training and have some training record or certificate as evidence. Don't forget to include yourself if you plan to do some auditing, if having a CQA is also acceptable as an alternative