Jin is an open source, cross platform, graphical client for chess servers, written in Java. Jin can run either as a standalone application (available at this website) or as an applet, directly from your browser (available at the chess server's website).
Currently supported servers are the Internet Chess Club and the Free Internet Chess Server.
This program does require Java and I believe it will access the Portable Java
Download Jin Portable 2.14.1 Development Test 1 [17.7MB download / 20.2MB installed]
Development Test 1 (2010-04-13): Initial release
Please test this to ascertain whether I have handle the Java in an appropriate manner as far as reg keys and such.