Shouldn't be too bad. I installed stainless headers in my car instead of Pacesetters, but they are very close in dimensions. I didn't need to lift the motor at all, jut unbolted the stock stuff (soak the bolts in PB Blaster the night before, helps tremendously) and slid in the new headers. I had the front of the car up on ramps, which worked perfectly and gave me just enough clearance. Since I was working by myself, I slid in the headers from the bottom, hung the flamges on the spark plugs (very carefully, don't break any plugs) and then came up to the top and bolted them on.
Another thing to consider is changing the motor mounts while you are in there. I made the mistake of leaving them alone, and my y-pipe would bang the floor under acceleration. Very annoying. So I ended up pulling the headers back out and installing poly motor mounts. Its not a fun job, but its worth it. The drivers side mount was in the worst condition, it looked partially melted.