Download Flex SDK (Free) from http://www.adobe.com/products/flex/flexdownloads/
Follow installation instructions from http://edutechwiki.unige.ch/en/Adobe_Flex


download actionscriptid.vim file from  http://www.vim.org/scripts/script.php?script_id=2941
follow installation instructions from http://www.vim.org/scripts/script.php?script_id=2941
install details
Throwing it into you \\\"syntax\\\" directory 
Then adding this line to your syntax/actionscript.vim 

runtime! syntax/actionscriptid.vim 

sudo cp ~/Downloads/actionscriptid.vim /usr/share/vim/vim72/syntax/
sudo cp ~/Downloads/actionscriptid.vim /usr/share/vim/vim70/syntax/