When I did the training (Fresenius), the "certification" consisted of getting to the point where the home care RN who was training me was convinced she could sign the forms stating that I was fully ready and prepared to do it on my own. I suspect that this sort of sign-off if what she is referring to as being "certified". There is a final exam where the RN comes to your house and watches you go through the entire procedure. Remember, you are part of your clinic's success/failure rate - and they will do everything they can to make sure you succeed.
As to links...
Training will consist of two topics - use of the machinery and cannulation. Chances are pretty good you will be taught both sharp and buttonhole cannulation, and then do buttonhole at home. The links under the for professionals section at
www.fistulafirst.org are pretty good - see
http://www.fistulafirst.org/HealthcareProfessionals/FFBIChangeConcepts/ChangeConcept8.aspx for starts. Also, google for papers by Stuart Mott (a RN who is known as the guru of cannulation).
You can often pick up additional tips by reading the medical papers. One Stuart Mott tip I was not taught in training was don't hub the needle when doing a buttonhole. I asked the home care RN about this and was told "good idea, do it that way".