An instructional video on how to do this!
And why would you want to do such a thing? Watch the video to find out. ^_^
3/27/15 Edited to add:
I was in a rush when I posted this, but I should have said that Dollar Tree wire is not treated, meaning, it is not tarnish resistant, thus it only costing a buck. If you are concerned about your doll's body, then do not leave the wire on it for long periods of time because it MAY stain it and the same goes for clothing. My Monster High body has been Dollar Tree wired for 7 months now and it hasn't stained at all but that doesn't mean it wont. Better safe than sorry.
If you want to leave the body permanently wired then I would get treated wire that will cost you about $5 or $6. You can order Darice Craft Wire, 20 gauge 15 yards, from Amazon or pick it up at Michaels or Joanns.