This bundle contains a language grammar based on the one in the Actionscript 3 bundle, but stripped and modified for the haXe language.
Run this:
$ cd ~/Library/Application\ Support/TextMate/Bundles
$ git clone git://github.com/sicher/haxe-tmbundle.git haXe.tmbundle
$ osascript -e 'tell app "TextMate" to reload bundles'