The JModelica.org Eclipse plugin allows textual editing of Modelica code, error checking of models and browsing of the class structure of loaded libraries (e.g. MSL).
 
The plugin is available for installation from an update site: http://www.jmodelica.org/downloads/eclipse-plugin 

To install the plugin:

1. Add http://www.jmodelica.org/downloads/eclipse-plugin as an update site (see http://marketplace.eclipse.org/updatesite/help for instructions for the latest version of Eclipse).
2. Select the entire category "JModelica".
3. Click "Next" and follow the instuctions.