Inside the chair (built-in)

("Hidden" under the chair's base plate cover, joined to the air/waste/water plumbing in the floor under/in front of the chair)

Images are from the VK-A2000 (black leather) model. 

Outside the chair (external)

(As a separate unit in a box usually positioned next to the spittoon/cuspidor side box. This is joined to the air/waste/water plumbing on floor on the side of the chair instead of "under" the chair. )

Images are from the VK-A2000 (black leather) model.

Observe how the box can't be placed right under the spittoon due to lack of space and will therefore need to be placed slightly to the side.