Eureka Steganographer allows embedding text messages and entire files into graphic images, mp3's, etc. Eureka Steganographer is available for Windows, Mac and Linux. This version is not compatible with version 1.
Actually there is no install for this application. You can run it right where you unzipped it, or copy the files unzipped wherever you want them.
The program has a Help file to guide you on how it works, although it is simple enough to run without much assistance.
You probably need to issue a chmod +x stegan before it can run. On some linux systems you may also need to issue a chmod +755 stegan.