Single select Tag instead og multiple

It’s the greatest plugin so far for buddypress to allow posting article without entering wp-admin area. I use it in my citizen journalism website http://citizentell.com and have no problem at all except the tag selection checkboxes which, unlike the category selection, can’t be forced to single selection instead of multiple

How to make it a single select checkboxes?

http://wordpress.org/extend/plugins/social-articles/