Your joints will definitely release over time with a regular Kundalini Yoga practice and some attention to good form. Yoga Bliss Hips and the Hip Opening segment from the new Yoga for Beginners & Beyond: Stretch, Strengthen, & Be Stress Free would be very good choices for you.

If its possible for you, taking some live classes from a teacher well versed in alignment would be a good idea.

For now, you can raise yourself up with a folded blanket sitting on the corner edge so that the thighs can fall more easily out of the sockets. As you bend your knees to cross the legs, try tucking your palm in the crease behind the knee as you bend and once in position, slide your hand out. This will create more "space" in the joint.

There is a mind/body connection which is expressed physically but it could be simply that your hips are small.

Also, try the So Darshan Chakra Kriya Meditation (see listing in this archive) or the Sa-Ta-Na-Ma Meditation which is on both of our Yoga Quick Fixes and Yoga House Call DVD's.