Upgrading the BMLT Root Server is very easy. Upgrading Satellites, is even easier.
First, Back Up
Before upgrading anything, you should make a full backup of all the source and the database[s]!
The BMLT has been designed to smoothly upgrade, but, you know, stuff happens…
Upgrading the Root Server
In order to upgrade the root server, you first download the current stable version of the root server (downloads a zip file), then simply copy the modified version of the /server/config/auto-config.inc.php file from your current installation, over the default one.
Then, you put the updated main_server directory over the old one, replacing any previous files, and deleting any ones that have been removed.
If there are any database changes, the first call to the main index file will make them, so make sure that you call it at least once.
The sever version is displayed in the extreme lower right corner of the root server index screen. The current root server stable version is [advanced-xml:serverversion].
Upgrading the Satellites
Follow the directions in the satellite installation docs. The WordPress satellite can be auto-updated. The Joomla Satellite must first be uninstalled, then reinstalled. The The WordPress and Drupal satellites will preserve the previous settings, but The Joomla Satellite requires that you re-establish the settings after an install.
Upgrading the the standalone satellite is pretty much up to you, as it is dependent upon how tightly you have integrated the file into your server.