cheerium
I tried looking up some of the texts mentioned by Scion but was having difficulty, so the guide would be handy in that regard but it's all good, now everyone knows it's not available anymore at least.
While we all wait for his book, this doesn't mean it is impossible to study without his guide. The decans shed light on the minors, but act mainly to reinforce or support the already established methods for determining the card's meaning and significance. Scion in his guide relied, as far as I can tell, on already readily available text such as the Picatrix and Ibn Ezra. Both of these as-is, without Scion's accompanying text, would provide great insight into the decans, although he did make use of other sources.
I hope that by mentioning what is actually in the guide I haven't said something I shouldn't.