The following books cover kyerim/generation stage practice:
The Kalachakra Tantra by HH Dalai Lama (on Kalachakra tantra)
Union of Indivisible Method and Wisdom by Geshe Thubten Loden (specifically on the Yamantaka system)
Swift Path to Kechara Paradise by Geshe Tharcin (generation stage of Vajrayogini)
There are more general books that include instructions on the philosophy, psychology and spiritual technology behind generation stage practices that I highly recommend for practitioners of all deities:
Principles of Buddhist Tantra from the late Kirti Tsenzhab Rinpoche
http://www.wisdom-books.com/ProductDetail.asp?PID=22281To understand the method of Bringing the Three Bodies into the path which is the crux of generation stage practice this book is indispensible:
Death, Intermediate State and Rebirth in Tibetan Buddhism by Lati Rinpoche and Jeffrey Hopkins
http://www.wisdom-books.com/ProductDetail.asp?PID=22281