I mounted mine to the 'X' supports right above the air dam and infront of the radiator. No need to remove the fan shroud and all that, just slip right up in from underneath where the air goes into the radiator.
I prefer the oil to first go thru the stocker in the radiator then thru the external cooler, this way the trans temp can be cooled down alot more than the coolant temp, the other way your trans oil temp can only be cooled down to whatever the coolant temp is in the radiator, which will be well over 120 degrees.
Some will debate that this causes your coolant temp to be higher, but I bet its not more than 5 degrees, and 5 degrees coolant temp won't hurt anything, but 40-60 degree cooler trans temp can mean alot longer tranny life. The radiator is alot bigger and get disipate heat alot easier than the external tranny cooler can, plus the radiator has fans to pull the air thru when at lower speeds which is when the tranny generates the most heat in everyday driving.
Once the convertor locks during cruise, the tranny temps should drop quickly.