mjcq is a command-line based ICQ client program written in pure JAVA and so is cross-platform. It uses the "jcq2k ICQ2000 OSCAR protocol plugin" library developed by Filippov Evgenii. (http://sourceforge.net/projects/jcq2k/)
mjcq provides an interface
Jatobo (Java TOC Bot) is another Bot connecting to the ICQ and AIM networks via the TOC2 library. For that purpose it uses Jatoli (Java TOC Library) also included in this project. Feel free to use it for your projects.