Sure! I'm basing all of the following off of the factory demo midi_fx/alternative_tuning.
As long as you know how many cents you want to adjust each note, all you have to do is multiply their values by .64 and enter them into the table.
I wanted to tune to just intonation with C as my root note. I used the following list of cent adjustments (these are hard to find, but I knew there was one in the midi manual for my Roland Juno-Gi):
C: 0 C#: -8 D: +4 D# : +16 E: -14 F: -2 F#: -10 G: +2 G#: +14 A: -16 A#: +14 B: -12
Then, multiply each of these adjustments by .64 and type the resultant values into the sliders of the table (the first slider is C and they move up chromatically, you can ignore the extra sliders).
It's not an ideal solution for temperaments, but it works for this specific application. I'm not honestly sure if these cent values are transposable and haven't tried yet, but I would imagine they are (I'm used to tuning with my ear and beat speeds rather than math).
I do wish there was an alternate way of doing it in which one could set specific frequencies for each note in a tempered octave, and there probably is, but that is beyond my knowledge at this point. If anyone else has ideas on that, I'd certainly welcome them!
Hope this helps!