After lots of Google and forum searches, I pieced things together from different places to figure out how to connect my new TD-17 to EZ Drummer in Studio One 4. I thought this info might be useful to other newbies like me and save hours of trying different connections.
Connect TD-17 USB to PC USB. Turn on the TD-17
In TD-17 > Setup > USB > USB Driver Mode > Vendor
In TD-17 > Setup > MIDI > Local Control > Off
In Studio One, add the TD-17 as a new device
Add a track for the TD-17 with EZ Drummer
In EZ Drummer go to Menu (top right) > Settings > E-Drums
Click on MIDI Mapping to get drop down menu. Select Roland.
Play around with High Hat Pedal Correction to find preferred setting.
Record the drum track in Studio One
Right click on the drum track. Select Instrument Parts > Explode Pitches to Tracks
Select None for the Instrument Output on the exploded tracks. The drag EZ Drummer to all the tracks one by one. This allows editing and mixing of each individual drum pad.
Edit each drum track as necessary.
Hit F2 to edit a drum track. Click the arrow tool and select all the notes in the Editor. Click and drag one velocity bar, up. All the velocity bars will go up as a group. This is if you want a velocity consistent sound.