Lay the pan liner over the shower alcove so the entire area is covered by the liner.
Trim the liner along the two sides of the corner of the shower stall, so it extends up the wall about a foot, covering an area slightly taller than the shower's curb, if there is a curb. If not, make sure the liner runs up the wall at least 6 inches. Trim the liner with a razor for best results.
Tack the liner into place with a staple gun and staples, or tack nails and a hammer.
Flatten the liner along the base and pull it forward over the front edge of the neo angle shower by hand. Trim along the edges of the neo angle with a razor so the liner folds over the neo angle completely. Tuck and fold the liner under itself as necessary to accommodate for the angle of the shower.
Staple or tack nail the liner in place as you tuck and fold. Keep the liner flat as you secure it in place.