I can't really give too much advice as I've just started trying my hand at kiltmaking. But I can say the book is great in that it shows common errors in kilt making and how the kilt should look.
As for other resources, you seem to be wearing a kilt in your avatar. Having a kilt to look at is a great resource, at least for me; I am a visual person and prefer to see things rather than to have them described to me.
Barb's "art of kiltmaking" only deals with knife pleating. I'm sure it can be of use for planning to make a box-pleated kilt too but I would search DIY threads for actual box pleating instructions.
Good luck!