What do we do? New Mexico abandonment, Solider deployed?

My husband is deployed, and will not be back until Sept. 2011. We currently live in TX. His ex wife has abandoned their son in NM with her uncle. Her uncle called me and my husband asking us to come get my husband son(4yr old). The uncle has not seen the mother/ex wife in about 4months. My husband is paying child support for his son, ex wife has not and will not let him see their son.< in the divorce it say the gets visitation rights. Ex wife is on drugs and we and her family have asked her to get her life together but she does not want to. I have called CPS and they told us the uncle can not give the son to us because the mother left the son with her uncle and if the uncle decides to abandon or not take responsibility, the the son will become a warden of the state. We do not want this but we do not know where to go or who to talk to so my husband can have his son in his life and take care of him properly. Does anyone know what we need to do or can do so we can get the process rolling so when my husband comes home from tour, we can have everything ready.