Update drush on Windows Bitnami wamp + drupal module

Hello, I try to update the drush provided in the bitnami drupal WAMPstack module using "drush selfupdate" to no avail:

C:\\Program Files\\BitNami WAMPStack\\apps\\drupal\\htdocs>drush selfupdate

A newer version of drush, 7.x-5.4, is available. You are currently running drush version 5.1. The update process depends on how you installed drush. Some common update commands are:pear upgrade drush,git pull,drush dl drush --destination=[/path/to/drush]. To disable this check, put "$options['self-update'] = FALSE;" in your drushrc.php configuration file.

I use the following configuration

• bitnami-wampstack-5.3.14-0-windows-installer.exe
• bitnami-drupal-7.14-0-module-windows-installer.exe

Can someone provide instructions ?

I already tried the ones provided in the error message. To make drush work I had to tweak the path environment variable.

Thanks for your help.