hi
i've just played a little with joomla jinstaller and changed it to make wbinstaller
wbinstaller job is to download directly the wb.zip archive (stable, update, lastest svn) and expand it on your server.
so it install wb in few second instead of the usual ftp (no interrest if you have root access to unzip in command line) but can help
for the stable / update it make an error as it seems it can't download the file from the offical link (it need a direct link)
so i'v added a link for wb from my demo page to test
it works for the svn version exept it includes the branches/wb2.8/wb...

you can easily add your own dload link with a personnal modded wb to install
elarifr