jQuery Grid Plugin - jqGrid

Is there a way for me to add custom CSS to a grid header cell? Ideally I'm looking for a propery to set in the column model definition, much like the 'classes' property works for the DATA columns. I'd also prefer to have it set on render rather than procedurally changing the CSS after the grid loads. My goal is to have some of the columns' titles rotated 90 degrees to save space and rotating the labels after the grid loads will cause the screen to have a weird jitter (I suppose I could hide the whole table behind a layer until its done, but still...)

Any help/suggestions appreciated.