For m. 1, I set the tuplet definition to 6 quarters in the space of 4 quarters, and in m. 2, 3 quarters in the space of 2 quarters.

Here is a link to my tutorial on tuplets: https://www.dropbox.com/s/5dg0bv5y9zdp2ld/Tuplets%20with%20Simple%20Entry.pdf?dl=0

Thank you very much, Mike!

But how about something like this? Since human players know what to do with this, I figured by now Finale would, too.

It worked for me. I entered the quarter, set the triplet as 3 quarters in the space of 2 quarters. Then, I dotted the first note and entered the eighth and the quarter. What you're dealing with is a quarter note triplet, even though the first note is dotted.

I keep trying that. Won't let me enter the last note.

edit: i had a standard triplet in another track which seemed to interfere with creating the dotted-ish figure. I was able to do the above by first creating it in an empty measure, then copying the figure over with 'show active layer only' enabled. 

In this case, it shouldn’t matter, but check to see if Check for Extra Notes is UNCHECKED in Simple Entry Options.