Soak hickory chips in water to cover for at least 1 hour.
Drain.
Saute onion and celery in butter in a medium saucepan until tender.
Add dressing mix, water, salt, and pepper, stirring well.
Remove dressing mixture from heat, and set aside.
Trim excess fat from pork chops; make pockets in chops, cutting from rib side just to beginning of fat edge of each chop.
Stuff pockets of chops with dressing mixture, and secure with wooden picks.
Set aside.
Prepare fire in a covered grill; let burn until coals are gray.
Rake coals to one end of grill; place wood chips over hot coals.
Place chops at opposite end; cover with lid.
Grill over indirect heat 1 hour or until desired degree of doneness.
Turn and sprinkle with liquid smoke every 15 minutes.