I installed the bonus merchants, but can't find them. where are they?

One is in the back of the adventurer's mart. The other is in the copper coronet, usually standing near the fire pit thingies, though some people have trouble finding him so just talk to all the people there and you'll eventually come across him.

Deidre is in the Adventurer's Mart, on the level above Ribald.

Joluv (he's dressed as a nobel) is in the Copper Coronet, in the middle of the area where you find the 'bbq pits' (that's what they look like to me).

Happy adventuring!