Getting magic properties on scribed books works the same for Magery, Mysticism, and Necromancy. The chance of getting magic properties on the book is determined by your skill in the respective magic skill. About half way down on this page:
UO Stratics - Inscription has details on scribing spellbooks. You will want at least GM skill (in the book's respective magic skill), so you can get up to three properties on a spellbook. Above GM will give you a better chance at getting properties. Personally, I do not scribe spellbooks at less than 110 in the respective skill.
EDIT: FYI in the future, Inscription topics are found in the Spellcaster Forum.
Stayin Alive,
BG