I just found this from mozilla:
Support for the CSS 3 syntax for cursor values got added in Gecko 1.8
(Firefox 1.5):
cursor: [ [<x> <y>
]?,]* keyword It allows specifying the
coordinates of the cursor's hotspot, which will be clamped to the
boundaries of the cursor image. If none are specified, the coordinates
of the hotspot are read from the file itself (for CUR and XBM files)
or are set to the top left corner of the image. An example of the CSS3
syntax is:
.foo {
cursor: auto;
cursor: url(cursor1.png) 4 12, auto;
}
.bar {
cursor: pointer;
cursor: url(cursor2.png) 2 2, pointer;
}
/* fallsback onto 'auto' and 'pointer' in IE, but must be set
separately */ The first number is the x-coordinate, and the second
number is the y-coordinate. The example will set the hotspot to be the
pixel at (4,12) from the top left (0,0).