Spacemunkee, heres a bit of brake science for you. ;)
When a pad hits the rim it will cause friction, if you set the pads up at an angle to the rim, then when the forst part of the pad contacts it will start slowing you down, the harder you pull the more contact area and therefore greater friction.
Now, with a trials brake we don't really need to angle our pads to the rim for modulation, in fact a brake feels and works better for trials when the pads are flush with the rim. If the pads are flush with the rim all the pad material will make contact (almost) immediately and the pads will bite, the bite makes the pads try to move and therefore produce a vibration giving the squeak we all know and love.
That is why trials brakes squeak, and a well set up pair of pads will almost always squeak, this is why a squeaking brake is a working brake.
Also Fat-Dan, take the pads of and sand them lightly on a flat surface, give the rim a grind, spray muc off on it, set up your brake using the 2p trick and then ride around alternately dragging and grabbing the brake. See if that helps, it can take a few goes (Y) This will hopefully make the pads wear flat to the rim. improving your braking.