Thanks to everyone's advise I have completed the installation of the auxiliary transmission cooler. I used B&M supercooler, part number B&M 70264. You can see roughly what my installation looks like on the attached image.
A few comments are necessary here:
1) I suspect that moving the cooler up a few inches would probably be better, because there is more airflow right in front of the long horizontal hole in the grille. However, it was not physically feasible to install it up there. I had to pull the plastic fasteners from the other side of the AC condenser and this is how far it is physically possible to slip my wrist behind it without suffering from serious cuts or breaking things. (And my wrists are pretty narrow as is). This part was a PITA.
2). The fact that the aux cooler hoses are exposed to the thin horizontal oval hole in the grille is a cause for a slight concern because it is theoretically feasible that debris from the road could penetrate this space and cause the damage to the hoses. This is not so theoretical as there are some clearly visible dents on the AC condenser fins, surely from road debris. However, I believed that putting it up side down is better in order to prevent pockets of air from forming inside of the aux cooler, thus reducing its effectiveness.
PS: Last question, just how tight should I fasten the hose clamps?