JDK is not available as a portable zip unfortunately. However, you can:

    Create working JDK directory ("C:\JDK" in this case)
    Download latest version of JDK from oracle (for example "jdk-7u7-windows-i586.exe")
    Download and install 7-zip (or download 7-zip portable version if you are not administrator)
    With 7-zip extract all the files from "jdk-[6-7]u?-windows-i586.exe" in directory "C:\JDK"

    In command shell (cmd.exe) do the following:

    --> change directory to directory C:\JDK\.rsrc\JAVA_CAB10

    --> execute command: extrac32 111

    Unpack C:\JDK\.rsrc\JAVA_CAB10\tools.zip with 7-zip

    In command shell (cmd.exe) do the following:

    --> change directory to C:\JDK\.rsrc\JAVA_CAB10\tools\

    --> execute command: for /r %x in (*.pack) do .\bin\unpack200 -r "%x" "%~dx%~px%~nx.jar" (this will convert all pack files into jar)

    Copy whole directory and all subdir of c:\JDK\.rsrc\JAVA_CAB10\tools" where you want your JDK to be and setup manually JAVA_HOME and PATH to point to your JDK dir and its BIN subdir.

Thats all. After this you'll be able at least to use javac.exe