You won't have time to set trap rivets very strategically in the train station itself, so I recommend first setting up some in the ticket room before you talk to Tenenbaum. After dispatching the splicer banging at the ticket window, set trap rivets at about head height (for a headshot kill ;), it actually works!) around the two gates and when the gates open the splicers will be running into a trapfest. ;)
The splicers themselves will be streaming in from a couple of raised doorways in the station (think splicer vents ;p) and may even stay there to throw some cover fire and fire bombs your way. You will run out of rivets eventually, so once you get out there, aim for those vents, one immediately to the left and the other further down on the right. The left one will most likely be the one most "populated" when you go out.
Pick them off and you'll see this achievement pop with a thank you from Tenenbaum and directions on how to proceed with... Sinclair.