The one and only cyclocross book in the world is Simon Burney's "Cyclocross Training & Technique." It covers everything from equipment to training to clothing to racing. It's a bit old, but most of it is still valid.
Training for mtn bike races and cross races is pretty different, but there are several components necessary for each. I would assume you'd be training for the mtn bike season and then seque into training for cross in July or August.
First, you need a strong aerobic base. This means good, solid road miles -- steady and a low to moderate intensity level. Most mtn bikers do their aerobic training on the road because you can't get those long, sustained efforts on most mtn bike trails.
To develop your own training plann, I'd recommend Joe Friel's book (Ned Overend co-wrote the mtn bike version with him). Friel is really a self-help, do-it-yourself manual that will teach you how to assess your strengths and weaknesses and then develop your own training plan.
Mtn bike training is very transferrable to cross, but there are some different requirements. Think about how the races differ -- mtn bike races will be 90 minutes to 2 hours for the most part, so you're not going red-line the way you are in cross. You're also not running. Cross races are short and hard with fast transitions. For cross, you'll do more short intervals along with time trial paced efforts (2 x 20s).
I'm rambling....sorry, Saturday night and I'm tired. I probably shouldn't have started to answer this but I got so excited when you said you raced with 40 CAT4 women. Woo hoo!