Sublime-Text-2-Velocity-syntax-files is a project mainly written in ..., it's free.
Velocity Template Langue Syntax Highlighting for Sublime Text 2
This is some very basic install and set up instructions. If you want to jump in a help develop this more. Take a look at the Syntax Definitions documentation put together by the Sublime crew. Its a pretty sweet collection of documents and should be able to get you started. Happy codeing.
Place the Velocity dir in the packages directory. /Users/${USER}/Library/Application\ Support/Sublime\ Text\ 2/Packages