having played against a fair few piechuckers, here's my tips:-
1. Patience - take a proper look at the bowler. Piechuckers rely on slow surfaces to stop the ball coming on to the bat, so you'll need a few overs to work out what he's doing.
2. Shot Selection - try and pick up singles, tip and run, etc and initially try and use the lack of pace to "work" the ball into gaps.
3. Go Ugly - it's inevitable that you'll have to hit in the air. It's not always cowcorner, sometimes you can pull or pickup over leg or loft over mid-off. Choose the ball carefully and pick your spot as one may come down only once every 3/4 overs.
4. Footwork - if your lucky and the keeper is rubbish he'll be standing back, get yourself out of the crease - yards down the track for your guard. If your not happy doing that (I've been 5 yards out of my crease but some people never move) a bit of a shimmy down the track has much the say effect. Important thing is it mucks up his length.
Don't - go across the line, slog early, play hard wicket shots.