I am in the same position. I am trying to print address labels onto a 100mm x 62mm shipping label using a Brother QL-650. The printer needs a margin of 1.5 mm on the long side and 3 mm on the short side. The printer comes with a program (P-Touch) that can print right up to these borders, but when I try to print an address label (from safari) there is always an extra 7mm border at the top (so 10mm) and a 15mm border at the bottom, which knocks 22mm of printable space of the label.
I have spent 3 days messing with CSS, php, printer settings, and any other levers I can get my hands on, and nothin' Zip. Can't even cut and paste into the labelling software because it prints the HTML. Hate it.
I have tried Pages and TextEdit and they also have the insane margins. Perhaps Apple has hired an ex-Microsoft person to do this, who is trying to helpfully guess what we want then hard-wire it in. For our convenience, of course.
Perhaps Snow Leopard is better - but I don't have time to deal with all the things it will break.
I hate computers. Hate 'em. Should have been a plumber like my daddy said. I would be at the bowling alley by now, with the Porsche parked outside, and the blonde floozy with a voice that cuts glass bringing me drinks and filing her nails. "And," the Daddy always liked to point out, "ya can't outsource plumbing to Bangalore." **** right.