If you click on the NPC and use the command showvars on console, you can scroll through all NPC variables and you can find a variable called HomeLocation. This variable stores the cell ID number of the default home location of that NPC. I tried to change it with console commands, but it didn't worked. Also, the default home setting seems tied to Papyrus companion script, so maybe we'll be only able to change it when GECK arrives. And God knows when it will be made available.