Alot of the trails will be under snow but, there are some trails at lower altitudes that could be open. Depending on what you want to conquer.

Kingston Peak, China Wall, Slaughterhouse, and some others.

You may be able to hook up with some of the guys from www.RMXC.net and go out with them.

There are also some good books on the trails as well.

Some good links:
www.colorado4x4.org
www.rmxc.net
www.traildamage.com
www.4x4trails.net