Ok guys I am going to answer the actual question. Please don't jump in here with the mono stereo debate. That's not what is being talked about.
Answer: The dock connector itself cannot be set to mono. BUT the iPad can. Go into settings, general, accessibility. That will take care of the mono issue if you are using the dock connector.
If you don't want the iPad in mono then you need to use 2 channels and leave both the left and right iPad signals in the center.
If you don't want to use 2 channels (only 1) then you have 2 options. 1) set the iPad to mono, 2) use a 1/4 inch stereo to mono adapter at the end of a 1/8 in cable. They cost around $4 at radio shack. I always keep one in my gig bag just in case something comes up where I may need it.
