You can checkout the UIMA Projects as Eclipse Projects, using the Eclipse SVN plugin. When you do this, you should check them out as plain "projects".
If you've checked out all of the projects under uima/uimaj/trunk, you can build all of them and set all of them up for Eclipse by
cd-ing to uimaj and issuing the maven command:
mvn install eclipse:eclipse
You can skip the rest of this, if you've done the above. What follows are instructions you can use if you've only checked out part of the uimaj/trunk.
If you are checking out less than all of the projects, you
will need to check out (also) the uimaj project; this holds the parent POMs needed by maven for building UIMA.
Once you have the uimaj project checked out, cd to the directory where you installed uimaj and do mvn install -N to install that POM in your loocal repository. Then cd to uimaj/eclipse-plugin-superPom and do mvn install -N to install the super POM for the eclipse plugins. You only need to do this once, or when these POMs change (for instance, for a new version).
The Eclipse plugin manifest information is kept in the maven POMs - it is maintained in just one place and used for both maven and Eclipse builds. The maven eclipse:eclipse goal is used, following the maven build of a project, to configure the corresponding Eclipse project so that it "works" in Eclipse.
You can do both of these goals in one maven command if you want to. To run these, cd to the directory of the plugin you want to work on, and do
mvn install eclipse:eclipse
This runs the maven build (the install life-cycle), and then follows it with the eclipse:eclipse goal which configures the corresponding Eclipse project so that it works in Eclipse.