Step 3: Add Rim piezo sensor
A breakdown on modules that I know:
Alesis DM5 does not allow double zone but does have enough trigger inputs (12) that you could wire a drum a little differently and actually have a double zone drum (Or cymbal).
the DM5 does have MIDI out which allows it to trigger software. a MIDI to USB adapter is needed to connect it to a computer.
Alesis i/O it has 10 inputs all of them double zone (When using a TRS cable) TRS picture on the following steps. This is not a drum module but instead a Trigger to USB interface, it does NOT produce any sounds but instead allows you to play software like BFD2 , Superior Drummer, EZ Drummer, Steven Slate Drums (which is the one I have) and more similar programs, The programs just mentioned are far better than any stand alone module due to the variety of sounds that you can get from any drum (some have over 90 velocity layers) making for a very realistic drum experience which mimics the real thing so closely you'll wonder how you played anything else before.
Roland Almost all Roland modules that you can buy today have MIDI out capability and at least some double zone inputs, more modern modules even have triple zone capabilities and even MP3 inputs to play along with your favorite tracks and some other fancy features that make them more than capable to support any electronic drum kit.
My personal preference is the Alesis I/O because of it's price and capabilities, it doesn't support triple zone but the only part where I would need it is for the ride cymbal. I am working on a way to do a triple zone cymbal on a double zone input, I think it has been done by racer52online in YouTube under "DIY Dual Zone Cymbal with Choke.MPG"