Converts keyword tv to seoPro Keywords objectCreate a snippet and run it on a blank page.

seoProKeywordConvertor

<?php
/**
 * Convert your keyword tv to  Sterc's SeoPro
 * 
 * Please read the following.
 *    Everytime you run this snippet, your keywords within seoPro will be overwritten.
 *    Make sure the TV exists before runnig this code.
 *    
 */
$seoPro = $modx->getService('seopro', 'seoPro', $modx->getOption('seopro.core_path', null, $modx->getOption('core_path') . 'components/seopro/') . 'model/seopro/', $scriptProperties);
if (!($seoPro instanceof seoPro)) {
  return '<strong>Oooops!</strong>. SeoPro does not exist in this MODx installation';
}
/** SET YOUR TV NAME HERE * */
$keyWordTV = '';
/** Set the seperator you used in you tv* */
$keyWordDelimiter = ',';

$tvCount = $modx->getCount('modTemplateVar', array('name' => $keyWordTV));
if (!$tvCount) {
  return '<strong>Oooops!</strong>. The given tv:' . $keyWordTV . ' does not exist in this MODx installation';
}

$resources = $modx->getCollection('modResource');
foreach ($resources as $resource) {
  $seoKeywords = $modx->getObject('seoKeywords', array('resource' => $resource->get('id')));
  if (!$seoKeywords) {
    $seoKeywords = $modx->newObject('seoKeywords', array('resource' => $resource->get('id')));
  }
  $keywords = $resource->getTVValue($keyWordTV);
  if (!empty($keywords)) {
    $arrKeywords = explode($keyWordDelimiter, $keywords);
    $seoKeywords->set('keywords', implode(',', array_map('trim', $arrKeywords)));
  }
  if ($seoKeywords->save()) {
    echo $resource->get('pagetitle') . ' keywords changed to seoPro Keywords ' . PHP_EOL;
  }
}

The Keyword values in line 33 could be trimmed to remove accidental whitespaces with:

    $seoKeywords->set('keywords', implode(',', array_map('trim', $arrKeywords)));

thanks for the feedback. I edited the gist.