Building CSRTool

If you're only planning on using CSRTool, then you do not need to build it. The csrtool-01-BuildXX-bin.zip file contains compiled jar files that will execute with just the addition of the BouncyCastle JCE Provider v1.35 and the JRE 1.5.0_9 (or greater). All you have to do is:

Unzip the zip file (which will extract the contents in a csrtool directory)
Copy the bcprov-jdk15-135.jar to the csrtool/lib directory; and
Execute the csrtool.jar file with: java -jar csrtool.jar to start the tool

However, if you want to build CSRTool from scratch, and/or modify it for your own use and rebuild it, then you need to do the following:

Getting the tools

Get the JDK 1.5.0_9 (or above) from http://java.sun.com
Get NetBeans 5.5 from http://www.netbeans.org. While you could muck around with the build.xml files to avoid this, the time spent modifying build.xml will exceed the time spent downloading NetBeans, installing it and using it - save yourself the grief
Get the BouncyCastle JCE Provider 1.35 for JDK 1.5 from http://www.bouncycastle.org
Extract the csrtool-01-BuildXX-src.zip file, which will create a csrtool directory in the extracted location

Fixing the location of the BouncyCastle JCE Provider

Startup NetBeans and Open a Project; point NetBeans to the csrtool directory from the previous step
When the csrtool project opens up, right-click on csrtool in the Projects tab, and select Properties
Select Libraries from the pop-up window
See if the configured location of bcprov-jdk15-135.jar matches the location of your copy of the BC jar
If it does, then click Cancel; if it does not match your location, you can either copy bcprov-jdk15-135.jar to that location, or delete this entry and create a new library entry and point your NetBeans configuration to where you have your BC JCE Provider jar. Select OK when complete

Fixing the locationn where the distribution is created

Select the Files tab in NetBeans, and expand csrtool, then expand nbproject and finally expand private
Right-click on the private.properties file and select Edit
Modify the property work.dir in this file, to reflect the location where the csrtool source was extracted on your computer. The default location in the file is /usr/local/workspace/csrtool/dist; however, if you unzipped the source zip file into a directory called c:\temp\csrtool, then you should change work.dir to c:\\temp\\csrtool\\dist or c:/temp/csrtool/dist (don't miss the double back-slashes for the Windows-style directory separator). NetBeans will create the newly-built distribution in this directory
Save the edits and switch back to the Projects tab

Building csrtool

Build csrtool by right-clicking on csrtool and selecting Build Project. The jar files are created in a subdirectory of csrtool called dist, while a zipped copy of the binary and source distribution (with your modifications, if any) is created in a subdirectory called zip
Run the tool by right-clicking on csrtool and selecting Run Project, or from a Shell/CommandTool window, go into the csrtool/dist directory and run csrtool by typing: java -jar csrtool.jar

Note:

If you'd prefer to use JDK6, you can do so; however, you will have to get the BC JCE Provider 1.35 for JDK6 and modify the Properties for csrtool in NetBeans to use the Java 1.6 platform before rebuilding. (Right-click csrtool, select Properties, select Libraries, pull down the Java Platform list and change the selection to JDK 1.6; if 1.6 is not visible in the list, you have to click Manage Platforms, select Add Platform from the pop-up window, specify the location of your JDK6 directory and close the wizard. You will then be able to select the JDK6 platform for the build process).