Changing lift gate struts on a wagon is a little more involved but still fairly easy. These insructions are for an 850 but should work on a 98 wagon.
1. Remove the courtesy light in the center of the rear roof trim by prying it out with a small screwdriver.
2. Disconnect the wiring and set aside the light.
3. Remove the roof trim by prying out the the two plastic caps and removing the two screws under them with a #25 torx driver.
4. Remove the rear pillar & roof trim by prying out the trim caps and removing the screws. Gently release these panels by pulling them free of their retaining clips.
5. Support the tailgate with a prop. Change one side at a time.
6. Disconnect the strut to body bracket. The strut ball-joints will pop out using a suitable pry bar.
7. Installation is the reverse.
Replace Trunk Struts: A How To