How to compile the IDE with Eclipse

I want to make an IDE MOD, so I have downloaded the source from http://arduino.cc/en/Main/Software

Then I unzipped the project folder to my workspace folder, and imported with Eclipse. Looks fine. Then I try to run it, and I'm asked about which Class to execute:

I selected Main. I'm getting an error: "processing-core missing".

If I select Base, I'm getting a dialog error saying "An unknown error occurred while trying to load platform-specific code for your machine". By the way, I'm running Windows7 64bits.

I don't know how to proceed, and I haven't found any reference or tutorial about hor to compile the source code of the Arduino IDE. Could anyone help me?

Here is a related thread http://arduino.cc/forum/index.php/topic,70547.0.html

No, no, no, that post discuss a different thing! I don't want to use Eclipse as my Arduino code editor. What I want is to take the Arduino IDE source files, load them as a JAVA project in Eclipse, and be able to compile it so I can do some changes to the oficial releases.

I have the same problem. Could you explain me how had you done this??