Installation:

Fire up Terminal, and enter the following two commands:

cd ~/Library/Application\ Support/TextMate/Bundles

If you're using Codaset, run: 
git clone git://codaset.com/scrogson/tm_bundle.git CakePHP.tmbundle

If you're using GitHub, run:
git clone git://github.com/scrogson/tm_bundle.git CakePHP.tmbundle

Finally, to activate the bundle in TextMate:

In TextMate: Bundles > Bundle Editor > Reload Bundles