http://stackoverflow.com/questions/10796464/transfer-ownership-of-a-file-to-another-user-in-google-apps-script

changeOwner.gs

//FROM http://stackoverflow.com/questions/10796464/transfer-ownership-of-a-file-to-another-user-in-google-apps-script

/**
* Change Owner of a file or folder 
* Run this as admin and authorise first in the script editor.
*/ 
function changeOwner(newOwnerEmail, fileOrFolderId){
  var file = DocsList.getFileById(fileOrFolderId);
  var oldOwnerEmail = file.getOwner().getEmail();
  if (oldOwnerEmail === newOwnerEmail) {
    return;
  }
  file.removeEditor(newOwnerEmail);
  var base = 'https://docs.google.com/feeds/';
  var fetchArgs = googleOAuth_('docs', base);
  fetchArgs.method = 'POST';
  var rawXml = "<entry xmlns='http://www.w3.org/2005/Atom' xmlns:gAcl='http://schemas.google.com/acl/2007'>"
      +"<category scheme='http://schemas.google.com/g/2005#kind' "
      +"term='http://schemas.google.com/acl/2007#accessRule'/>"
      +"<gAcl:role value='owner'/>"
      +"<gAcl:scope type='user' value='"+newOwnerEmail+"'/>"
      +"</entry>";
  fetchArgs.payload = rawXml;
  fetchArgs.contentType = 'application/atom+xml';
  var url = base + encodeURIComponent(oldOwnerEmail) + '/private/full/'+fileOrFolderId+'/acl?v=3&alt=json';
  var content = UrlFetchApp.fetch(url, fetchArgs).getContentText(); 
}

//Google oAuth
function googleOAuth_(name,scope) {
  var oAuthConfig = UrlFetchApp.addOAuthService(name);
  oAuthConfig.setRequestTokenUrl("https://www.google.com/accounts/OAuthGetRequestToken?scope="+scope);
  oAuthConfig.setAuthorizationUrl("https://www.google.com/accounts/OAuthAuthorizeToken");
  oAuthConfig.setAccessTokenUrl("https://www.google.com/accounts/OAuthGetAccessToken");
  oAuthConfig.setConsumerKey("anonymous");
  oAuthConfig.setConsumerSecret("anonymous");
  return {oAuthServiceName:name, oAuthUseToken:"always"};
}