Edlin is written with the intention that users should read it and modify it. Potentially the easiest way to get started reading the code is to look at the example script in the bin/ directory, or to read through the main method in one of the classes in the experiments package. You can do this without downloading the code in the cross referenced source.
To download a copy of edlin go to the Source Repository page. To re-build the package after you edit the files, you can use ant.
If you're not familiar with maven, it is probably easiest to download a snapshot rather than getting the code from subversion. In that case, you can import the code into eclipse just as you would any other project.
If you downloaded the code from subversion (rather than a packaged version), you can use maven to compile it and create an eclipse project for you. To do that, go to edlin/trunk/artifacts and run
mvn clean install
this will compile your code and install all packages Edlin needs. It might take a while the first time, since it will also be downloading trove and potentially packages that maven uses. To create an eclipse project,
cd to edlin/trunk/artifacts/edlin and run
mvn eclipse:eclipse
this will make an eclipse project for you. Then you need to start Eclipse in edlin/trunk/artifacts and click import/import/General/Existing Projects into Workspace. Then you need to set up the path to the M2 repository on your machine. Do this by right click on the edlin project in Eclipse, select Properties, Java Build Path, and click on the Libraries tab; then click the Add Variable button/Configure Variables button/New Button. In the New Variable Entry add:
Name: M2_REPO Path: The path to your repository. It is "your home directory/.m2/repository".
After that you should have an Eclipse project of Edlin without having any compile problems.