Reinstalling Radiator

My 2000 XJ has a dual core radiator, it has the standard coolant core, and then a seperate core for a transmission cooler.
My question is how do you add transmission fluid to the core before starting the engine. It seems like it would be bad to pump air thu it...
Any help is appreciated.

The tranny fluid goes through the transmission from the oil pan and pump and goes through the cooler last. So you don't have to worry about air in the cooler. As long as you don't run out of fluid in the pan, you are good to go.