To install a Vimball named "x.vba":
1. In shell:  vim x.vba
2. In Vim:    :so %

For more details:
http://vimdoc.sourceforge.net/htmldoc/pi_vimball.html
http://www.vim.org/scripts/script.php?script_id=1502
http://stackoverflow.com/questions/2033078/how-to-install-a-vimball-plugin-with-vba-extension