1) Install jdk.exe from the following location:
http://j2se.east/plugin/1.6.0_04-nightly/2007-07-19.12_44/windows-i586/jdk-6u4-fcs-bin-b199-windows-i586-p-19_jul_2007.exe

2) After JDK installation, Java(TM) SE Runtime Environment installation window comes up. Here under Feature Description, it does not specify how much space is required.
It just says "The Java(TM) SE Runtime Environment with European Languages. This requires MB on your hard drive"

It should specify the specific space requirement.