Answered Importing CSV to Update Template Variables (not ImportX)

$lines = file('path_to_csv_file', FILE_SKIP_EMPTY_LINES);

$count = 0;
$output = '';
foreach ($lines as $lineNumber => $value) {
    $data = explode(',', $value);
    if (count($data) != 3) {
        $output .= "<br />" . 'Mis-formatted line: ' . $value;
        continue;
    }
    $resource = (int)trim($value[0]);
    $tv = (int)trim($value[1]);
    $val = trim($value[2]);

    $tvr = $modx->getObject('modTemplateVarResource',
        array(
            'resourceid' => $resource,
            'tmplvarid' => $tv
        )
    );
    if (!$tvr) {
        $output .= '<br />' . 'Failed to get TVR: ' . $resource . ' -- ' . $tv;
        continue;
    } else {
        $tvr->set('value', $val);
        $tvr->save();
        $count++;
    }
}

$output .= '<br /><br />Updated ' . $count . 'TVs';
return $output;