Installation of the jcoverage eclipse plugin is via the eclipse software update manager:

find and install menu item

Choose to search for new features to install:

Create a new remote site: 

update sites to visit

Enter the details for the jcoverage eclipse update site as follows: 

new update site

The list of updates will now include http://eclipse.jcoverage.com/. Click on Finish.

update sites including jcoverage

Search results will include the jcoverage eclipse plugin as a new feature to install. Check the check-box and click Next. 

Review and choose to accept the 30 day evaluation license for the jcoverage eclipse plugin:

Choose Finish to install the jcoverage eclipse plugin: 

At the feature verification, choose Install All :

The jcoverage plugin will now download. Once the download is complete, restart your eclipse workbench: