I don't own any DirecTV equipment, but according to the file I took this from (at hifi-remote.com) a long press of the play button on the original remote sends this code. And the result is slow motion. A short press sends device 12, function 48, and that causes normal play.

Logitech can add it to your remote. Once it is in the remote, I expect that the PVR will begin slow play as soon as you press the button. I don't know if you will need to hold the button--I wouldn't expect that you need to.