Getting up and going is pretty straight forward.
mkdir -p ~/Library/Application\ Support/TextMate/Bundles
cd ~/Library/Application\ Support/TextMate/Bundles
git clone email@example.com:jpatzer/Tritium.tmbundle.git 'Tritium.tmbundle'
osascript -e 'tell app "TextMate" to reload bundles'
The trick to getting this to work is to tell TextMate to recognize your comments preference. To do this, you'll have to open up your bundle editor (Bundles > Bundle Editor > Show Bundle Editor) and navigate to the Source bundle. Open it and find the comments preference. In the Scope Selector write source.tritium.
Now you can do multiline comments with 'command + /' key combo (or any other that you'd like to define on your own).
At some point I may figure out a better way to do this (I'm probably missing something), but until then you'll have to go about things this way.
When you make changes to your Git-ified bundle in the Bundle Editor, you’ll need to Reload Bundles for the changes to show up in your repository. Then you’ll need to git add . and commit / push as you would a normal repository.