The jungle tile set will replace your swamp tile set from the expansion (version 1.5, make sure you have the patch installed). It will not work for people without the PC expansion. The mushrooms will be replaced by palm trees, and the water will be deep blue (like in the standard forest set). There are no changes in the gameplay (no new AIs).
To install it, simply run the exe file in your War2 directory and answer all questions with "yes".
This tileset has been made by Cameron Vine.
To get your old tileset back, either copy maindat.war from the CD into the war2\data directory or make a backup of that file first.