This is probably a dead issue by now, but as reference for those who might be considering this in the future:

As you look at the shift cable from underneath, you will see where the end "snaps" onto a ball stud. From there it continues towards the front and goes through a metal support.

If you look at the assembly in that area, you will notice a piece that is white in color, while the rest is black. That white piece is your lock tab.
Prying the edge with a screwdriver will allow it to slip out enough for you to make the necessary adjustment.

My problem, on the other hand, is that I have tried that adjustment, and I still can't get mine to shift right (won't go into Park) on a 1995 XLT 3.0 with 4R44E. The PRNDL switch on the tranny seems fine when moved by hand.

I think I am looking at cable replacement; but I do wonder: does the excessive slop in the shift lever indicate a problem in that area, and do those ever need to be replaced?