Carefully lay the tub upside down on towels or other padding on the floor so that the bottom of the tub is facing up. Remove the washers and nuts from the threaded studs on the bottom of the tub.
Place the bars over the threaded studs.
Thread a washer and nut onto each stud. Do not fully tighten the nuts; the bar needs to be able to slide back and forth until the foot is attached.
Fit the foot to the bar and tub. Secure the foot to the end of the bar with a flat washer, locking washer, and bolt.
Once the tub and foot are fitted correctly, tighten the nuts that were used to secure the bar to the bottom of the tub. Be very careful not to over-tighten the nut, this could strip the bolt and crack the tub.
After all feet are attached, flip the tub over and allow it to rest on the floor. Be sure to lift the tub by the rim only, never by the feet.