I don't think you can get more than a very small amount of upward motion on the cue tip, and I'm sure it isn't useful, but I think it's technically possible.
Yep. It's definitely possible. The shot requires a table size and cue ball position that allows you to position the cue's butt ON the table, and probably a cue ball contact at center ball or higher. One example would be a 9-foot table, with the cue ball on the third diamond (or less) of the long rail.
In Robert Byrne's Complete Book of Pool Shots (350 Moves) book, #80 describes this shot. I'm not 100% sure I'm remembering this correctly, but I think the thing that makes an upward stroke different than a normal (slightly downward) stroke is that if (for example) you shoot upwards with top right, you get cue ball squirt to the left AND swerve to the left. Something like that.
I'm not clear on the details, and I no longer have that book, but perhaps someone who does could look it up and fill in the details for us.
I made a (short and unedited) video of this stroke/shot a few years ago. Although you can't see the full cue in the video, I'm literally sliding the butt of the cue on the surface of the cloth, along the nook under the rail. It definitely requires a weird grip!
I agree that this shot is probably not useful for most game situations, but it is quite interesting for us techies.
FWIW, in the video, I'm playing 8-ball, and I'm stripes.
http://www.youtube.com/watch?v=28OuAj6r_Xg
I'm looking forward to more discussion/debate about this, especially if someone can look it up in Byrne's Complete Book of Pool Shots!
-Blake
EDIT: Here is the post from @pablocruz that inspired the video. His explanation sheds a bit more light on the subject. Hopefully Bob Jewett can tell us more about this shot...
"I recently was reading one of Robert Byrne's books and he was having trouble with a particular shot using outside english! The shot is where 2 balls are frozen along the long rail! He phoned Bob Jewitt and Bob was explaining that the cue ball was getting underneath the rail and couldn't be made, other than having your cue below the rail height and shooting up at the ball!! Something to that effect!
The shot Mr. Byrne diagrammed was a shot down the long rail to the corner pocket! The object ball was frozen to the long rail 1 diamond away, and the cue ball was frozen to the rail 3 diamonds away! Using outside english, you cannot pocket this shot!! I would be very interested in seeing the effects of that shot!! Maybe Bob or someone else can chime in on this one if I have the shot set-up wrong! I have the book out on loan!"
http://forums.azbilliards.com/showpost.php?p=4006769&postcount=52