My advice would be to, instead of finding a book, just analyse tone poems that already exist. Look at the program separately and see how the composer interprets it. Time the length of each section (and the whole piece) to see how long the episodes are. Analyse how good the program itself is (there should be contrasting events but with some linking theme/breaks between sections to establish the different stories). Look at how the composer interprets the program through e.g. harmony, texture, rhythm.
Style is really up to how the composer interprets the text (and the text the composer chooses), so is therefore up to you to determine what you do.
My suggestions for analysis are:
Respighi - Roman Trilogy (all three of them are excellent; Respighi wrote the program separately for each one so a good exercise would be to see how you would interpret it before you hear his version).
Sibelius - Lemminkäinen Suite/En Saga/Tapiola etc. (each "episode" is often a self-contained piece, if you want to see a different approach to the tone poem. Achieves a lot with little).
R. Strauss - Alpensinfonie/Ein Heldenleben/Also Sprach Zarathrustra/Till Eulenspiegel etc. (Strauss writes seriously long and complex pieces of music, which might not be what you're looking for, but the linking of motifs and structural rigour in particular are worth observing).
Smetana - Vltava (part of his Má Vlast cycle. A good example of how one theme can link very disparate scenes)
I'm sorry if this isn't helpful, but I genuinely think you will learn more about this sort of thing from analysing scores rather than finding a book on it (I also highly doubt there is an accessible non-academic book on the subject).