A Google search shows a number of ways to notate a microtone trill. Can you post a picture of which one you want? Then, we can see if Finale can do it.

how to add the bracket notes? thanks!

The Engraver Font Set font has the natural sign expression already done, as well as sharp and flat. I found the character for the quarter sharp (?) in the Engraver Font Set Extras font. A utility like PopChars is essential for this sort of work!