You need to access the Eclipse SETUP menu, tab to EXTERNAL, set ext1 to MIDI DOUBLE. Then set the CC number that corresponds to the controller. Then hold down the Hotkey or Parameter key you want to control until "modulate" appears, press the Hot Key for that, and set the control source to ext1. You can setup upto 16 external controllers. Also, make sure MIDI (SETUP) should be set to Omni.