4.) Create a launch configuration

1. Click the arrow next to the Run button (the green arrow) and select "Run Configurations..."
2. Right-click "Eclipse Application" and select "New"
3. "Main"-tab
   1. Name: Notes 8.5
   2. Run a product: com.ibm.notes.branding.notes
   3. Runtime JRE: Notes 8.5
4. "Arguments"-tab
   1. Program arguments:
      

      -personality com.ibm.rcp.platform.personality
      -product com.ibm.notes.branding.notes
      -debug
      -console

   2. VM arguments:
      

      -Xshareclasses
      -Drcp.home=${rcp.home}
      -Dcom.ibm.rcp.install.id=${install_id}
      -Drcp.install.config=user
      -Dosgi.install.area=${rcp.home}\eclipse
      -Dcom.ibm.pvc.osgiagent.core.logfileloc=${rcp.home}\rcp
      -Dcom.ibm.pvc.webcontainer.port=0
      -Declipse.pluginCustomization=${rcp.home}\rcp\plugin_customization.ini
      -Declipse.registry.nulltoken=true
      -Djava.protocol.handler.pkgs=com.ibm.net.ssl.www.protocol
      -Djava.util.logging.config.class=com.ibm.rcp.core.internal.logger.boot.LoggerConfig
      -Dosgi.hook.configurators.exclude=org.eclipse.core.runtime.internal.adaptor.EclipseLogHook
      -Dosgi.framework.extensions=com.ibm.rcp.core.logger.frameworkhook
      -Xbootclasspath/a:${rcp.home}\rcp\eclipse\plugins\com.ibm.rcp.base_${rcp.base_version}\rcpbootcp.jar;

   3. Click the "Variables..." button
   4. Click the "Edit Variables..." button
   5. Add the following variables
      • install_id=1255551475820
      • rcp.base_version=6.2.1.20090925-1604
      • rcp.home=C:\Lotus\Notes\framework
   6. Click "OK"
   7. Click "Cancel"
5. "Plug-ins"-tab
   1. Launch with: plug-ins selected below only
6. "Configuration"-tab
   1. Configuration file: Use an existing config.ini file as a template
   2. Location: C:\Lotus\Notes\Data\workspace\.config\config.ini
7. Click "Apply"
8. Click "Close"

Source from: http://lekkimworld.com/pages/eclipse34_notes851.html with minimal changes so that it fits to my environment and that I could use this content as basis for other howtos.