I solved the same problem in a simpler way:
In /modules/select.php, inside wpcf7_select_shortcode_handler function,
after $name = $tag->name:
`if(isset($tag->pipes->pipes) && !empty($tag->pipes->pipes)) {
$values=array();
$labels=array();
foreach($tag->pipes->pipes AS $ln=>$array) {
$labels[$ln] = $array->before;
$values[$ln] = $array->after;
}
}
else {
$values = $tag->values;
$labels = $tag->labels;
}`
