If you have the solid front sight block you can usually move the sight blade with careful use of a punch and a small hammer. Scribe a line right up against the block with a sharp point along the underside of the blade on the side towards which you are going to move the blade. You'll need to remove the foresight protector to do this. Then you'll be able to see how much you have moved the blade, and if necessary drive it back the other way in case you over do it the first time.
If you have the split foresight block, all you need is the screw driver mentioned above. Whack the end off an old screwdriver (better steel than the new ones, mostly), slit with a hacksaw and open/clean up with a flat needle file as required. The screw head measures about 70 thou or 1.8mm wide.