Yeah, you can do this yourself, and save yourself about $500. You may want to check the condition of your control arm bushings first, as they may need to be replaced too, depending on your mileage. My control arm bushings were shot on my '96 SE at about 110k, and I had to replace the control arms, since the bushings are pressed into place. The new control arms came with new ball joints installed, even though my old ones were still good. Control arms are considerably more expensive than ball joints, but its better to do this job once, not twice.
You may be in luck, because the '98 has redesigned control arms with stronger bushings, so you may not have the wear that I did.