What size opening does your blower have? I think that is where there is some confusion. I will try to take some pics of my setup later today but I will try to clarify now what I was trying to say.
I have a hose (about 1" i.d., 1.5" o.d) leaving my blower (I have a Dayton A/C 15cfm blower) and going up into the tower. Before the hose goes into the tower I cut a hole in the hose and inserted my beer line going into the tower so that the beer line is in direct contact with the cold air going into the tower.
I cut a 3" hose in the top of the kegerator to allow for adequate air return after the air leaves the hose in the tower.
If you want to put two hoses into the air hose, then you just will need a little larger i.d. air hose. I am assuming you have 3/16" i.d. beer line? 2" i.d air hose should do it allowing about 1" of return space.
I did the same thing as chad_schloss in this thread:
Danby Kegerator Improvements
(hole enlargement is on page two)
Hope this helps.