...Or use the Speedy Entry Tool:A. The secret key combination (Windows: Ctrl-"number key" ; Macintosh: Option-"number key") will tell Finale that you are about to enter a tuplet.
Ctrl-3/Option-3 will tell Finale that you want a "3 against 2" triplet.
The triplet duration will be defined according to the first value you enter: an 8th will give "three 8ths against two 8ths" ; a quarter will give "three quarters against two quarters". Therefore, if you are on a Windows machine, the 5 steps will be:
Ctrl-3 (I want a "3 against 2" triplet...)
4 (...namely a "three 8ths against two 8ths" triplet...)
LeftArrow key (...however, the first note shouldn't be an 8th...)
5 (...but a quarter...)
4 (...voila)
B. The "A" method will work for all mixed tuplets. But for "three 8ths against two 8ths" there is an even faster way, since that tuplet is Finale's default tuplet.
This time, let's take the 4 steps on a Macintosh:
Option-1 (opens the Tuplet Definition dialog box, which by default suggests "three 8ths against two 8ths"...)
Enter (...and that's what I want...)
5 (...The triplet should begin with a quarter...)
4 (...and end with an 8th)
Like Jims says, you can instead write two 8ths, and add a "swing" expression. Create a new document from Finale's Maestro Font Default Document. In its shape expression library there is an expression that tells the performer to interprete all 8ths all "rolled 8ths". If you also need "even 8ths", duplicate the expression, and edit the duplicate to say "even 8ths".
Peter