Approach Control assisted the pilot of an IFR C182 to a successful landing when the alternator failed compromising the pilot's ability to communicate.

Narrative

I was just south of the airport and noticed engine temperature decline; oil pressure falling; etc. I checked my settings for my prop and fuel. When I tried to contact Departure the call was not successful. I determined that it was an electrical failure and changed my transponder to 7700. I checked to make sure I could climb; turn left; turn right; and descend while I was also looking for openings in the cloud cover below. I was just approaching the mountain ranges and and the sky condition was overcast to broken. At that time Approach came on the radio and announced that if I could hear them that the airport was behind me at due north and to turn left or right. I tried to respond; but was not successful; but I did immediately turn right to 360 degrees. They also informed me of a telephone number to call if I could get service. I tried to turn my cell phone on; but was unable to get service. I was also informed that I was cleared to land XXR (that's what I understood). At that time I lost all communication. As I descended to around 4;000 FT; I received another communication; this time I was told to head 270 degrees and was cleared to XXL and that XXR was closed. I was able to respond and informed them that my electronics were not working properly. At that time I lost all communications again; but I was able to locate the airport and land without incident. After landing it was determined that the alternator had failed.