Freely

I would like to insert a "freely" solo into one of my scores. As in, the same note repeated several times, speeding up or slowing down (or both). I don't really care that much about playback (that would probably be impossible to implement); I just want to be able to write it. I have attached a picture of what it should look like. Note that it can be reversed and sometimes speeds up and slows down (and vice versa) immediately thereafter.