HighMem

First download Sun Java J2SE Development Kit from http://java.sun.com/
Filename should be something like jdk-1_5_0_07-linux-i586.bin
Short version:

apt-get install java-package
fakeroot make-jpkg .bin
dpkg -i .deb

Source: http://www.crazysquirrel.com/computing/debian/java.jspx