Basically I’m just looking to indicate to the performer that it should be “rolled” as it’s the final chord of a piece and the rest of the group has sustained notes. Something like the following (obviously this example is a whole note and wouldn’t fill the entire bar of 5/4)
Depending on what visual result you want to achieve, you can enter the notes as a tuplet and then add the tremolo (and then hide the number and bracket). For example, if you enter two half notes in a 4:5q tuplet, they will completely fill a 5/4 bar; the tremolo will display two whole notes. Or you could enter two dotted halves in a 6:5q tuplet, and then the tremolo will display two dotted whole notes.
Or without tuplets, you could do one 4 beat tremolo between half notes tied to a 1 beat tremolo between 8th notes.