The following steps will help is setting up jikes-rvm code on eclipse. There is nothing secretive or magical about this code but for the first timers there can be some inconvenience to setup the code on machine specially students. These steps are also available on jikes rvm website but couple of intermediate steps might be there that might cause trouble.
These steps are for Ubuntu or any other linux based system

1. Unzip the code to some folder.

2. Go to the folder using cd.

3. Type the following on terminal = "bin/buildit --eclipse localhost".

4. If Java_HOME is not set, it will prompt an error referring to this.
   Then go to /usr/lib/jvm(java installation location) and then the folder of the installed jvm ,["" have been used to emphesize on the commans...in practice don't use use these or it will be erronous.]
     for example, let  "/usr/lib/jvm/java-1.7.0-openjdk-i386" is the installation folder, copy the path using ctrl+l or mouse and again go to terminal and write
" bin/buildit --eclipse localhost -j /usr/lib/jvm/java-1.7.0-openjdk-i386". 
This time it must proceed with successful build otherwise the jvm path you have specified is faulty.

5. If it prompts "bison.exe" or "c++.exe" configuration error, it means you havn't installed these packages on your machine, use synaptic manager to install these.

6. This is a time consuming process and will take a long time to complete.

7. While in process it will search for some jars and if not found will proceed to download without your permission. So, if the jars are not handy, please be ready with internet connection.

8. After the build is complete, simply import it as existing java project in eclipse.

Your code is ready to be explored. It is also possible to build jikes using ant tutorial for which will be added later.

I have written a 2 page note that tells how one can start debugging and exploring Jikes's structure.
How to fiddle with JikesRVM