To install the bundle simply uncompress it and put the resulting folder into your (home)/Library/Application Support/ Folder
If you already have stuff in Textmate Support Folder, just copy the contents...
Then write in terminal: chmod +x ~/Library/Application\ Support/TextMate/lslint
(or use the command included into the Bundle ;)
You are done!!! (Open Bundle Editor - LSL in TextMate to see/change the shortcuts)