This is actually quite simple, once you understand a few things:
#1-what is midi and what does it do?
#2-How do I get midi into Pro Tools?
#3-little details that make or break function.
#1-midi(in the case of drums) is about as rudimentary as it gets. Midi gets a "note on" message from the trigger pad at a specific note value(like C3, D4, A2). These correspond to notes on a midi keyboard and also to sounds in the Roland module).
#2-Connect the Roland brain to the computer(USB) or your interface(MIDI cable). Either will work, as long as its configured correctly in the correct menu. For Pro Tools on Windows, in Pro Tools, Setup>Midi>Midi Studio. Here is where you create an "instrument", name it as you like(maybe "Roland Kit"), the brand and model are option(not required) and the crucial setting, the input port(how midi comes into the machine). In the case of a USB connection, it should show on a list(maybe the ONLY item on the list) as "Roland TD3 on USB[Emulated]"(or similar). Midi Output can be left blank for now(you would only need that set if you wanted to send midi back to the Roland brain to use the Roland sounds, but leave this for another time)
#3-with Addictive Drums, there will be an option somewhere(lower right corner?) for an E Kit preset(aka "midi mapping") for Roland(probably on a list along with Alesis and Yamaha). Call up a stereo Instrument track in your session and insert Addictive Drums in the top slot and mouse-click to make sure you can hear the plugin drum sounds. Hit the record button and play the kit and you SHOULD be hearing the plugin drums. Keep your playback buffer as low as possible to avoid latency while you record. Once you record your performance, you are free to edit/quantize the midi notes to your liking.
remember, you can also use (Pro Tools Transport window) the midi merge function so you could record the bass drum, then record over that and add the snare, so even if your playing is poor(like mine
), you can still build a good drum track.