You'd have to put the risers where the stock seat bolts go as opposed to where the seats mount on the bracket. The brackets have welded on studs for the seat mounting.
Second, is going to depend how tall you are. The brackets put you pretty close to being under the roll bar. I only have a couple inches. If I added a riser, I'd just about be hitting the roll bar.
2003 TJ, 33" BFG AT, 2" BL, 2" BDS spring lift, 55w DDM HIDs