[Eric Lambert]

Expanding on that a bit from the standpoint of creating/editing MIDI, you can create the MIDI parts in the plugin and have it play back in sync with ProTools (hit play on PT and the plugin starts, too), or you can have the MIDI on a ProTools track which will then be routed to EZD3. Functionally, there's little difference, it's just a matter of which editor you find easier to use, the PT track or EZD3's own MIDI editor.

If I'm using EZD3's MIDI libraries, I'll typically start by placing segments into EZD3's editor, getting the rough layout, then dragging that to a PT track and turn of Sync in EZD3.