If you plan to use crusher-X together with sequencers or other MIDI applications that run together on the same computer you need a Loop back device driver like the freeware "HUBI'S MIDI LOOPBACK DEVICE V2.5" (Win9x) or "MidiYoke" (WinXP) that you might find on the internet (see e.g. http://www.hitsquad.com/). Or you can use the VSTi Bridges.

Choose the Midi Input and Output devices. If you using the VSTi-Bridges it is not necessary to choose a device. If you choose a device the VSTi MIDI-Events are merged with the external MIDI-Events.

Check MIDI thru if you like to mirror the Incoming MIDI-Events at the Output. But be careful using it with Loop back devices or VSTi-Bridges, because of undefined midi feedback loops. 

Press Apply to make the changes active. Use the CPU Window to check for incoming MIDI events.

All parameters of crusher-X can be controlled via MIDI Keys or MIDI Controllers. Use Context Menu "Learn" Popup on each UI-Element and/or the Controller Window for assigning controllers.