IMO, your best and only course is to act as a true professional and carry out the training in good faith. This may be galling in the short term, but in the long run it's always in your favour. Attitude, dedication and team play count as much as knowledge and skill these days.

Documentation is a good idea. No need to skulk around though: discuss and lay out the training you think is needed with your manager, on paper; and include him/her and the trainee in documenting milestones. This is more than CYA; it's also a subtle way of reminding management of your qualifications.

Good luck!