Book:

http://www.amazon.com/Nidra-Re-print-Swami-Satyananda-Saraswati/dp/8185787123

Audio:

http://www.amazon.com/Relax-Into-Greatness-Rod-Stryker/dp/B000G0DBR8

It's possible to learn to do rotation of consciousness (one part of the process) without guidance. I'd suggest reading the book and looking for Amazon / iTunes resources that you can check out once you know more about the process. You might also record yourself reading the 5 + long & short form transcripts to use.