It's a heckuva a lot easier to just toss your track into Reaper and create the tape stop effect there. The default settings in Reaper will create the tape stop by simply creating a Tempo envelope that gradually slows down.
That means not only do you get the time slow down you also get the gradual (and proportionate) pitch dropping as well.
Trying to recreate this in SONAR is a hassle comparatively because SONAR does not link Tempo and Pitch together automatically like Reaper does so you have to futz around with some oddball procedures/tools.
Once you create your tape stop though you can of course just toss it back into SONAR. I do this shuffling back and forth from Reaper quite a bit because it does all the stuff that SONAR kind of sucks at.