I would argue that a base of 1.5 months after such a long layoff isn't enough. Before you start racing again, you need to fall in love with the dirt again. Really, take through January to really ride again with no intention other than getting in riding shape. Go discover the singletrack God. Ride some roads, too. Throw in some weight training. In January, find a plan that incorporates training periodization (I favor a 4 week schedule.) Hit some hills, ride some intervals and tempos. The race season here doesn't start until late spring.

I'd throw in SOME running, too. I always seem to get in shape quicker if I add running, but don't do too much, too soon. This is a good beginning program that goes well with cycling, if the person is in decent shape. http://www.coolrunning.com/engine/2/2_3/181.shtml