The Cougars (24-6) advanced after beating Arizona State in a five-set thriller last Friday and easily handling homestanding Hawaii in three sets on its home court last Saturday.
"We knew we would have a good team, but I am just proud of these girls," Olmstead said. "Maybe they have a chip on their shoulder because a lot of people doubted the decision we were all making [to have Hamson take a year off and return for the 2014 season]."
USC is 11-6 all-time against BYU. The national volleyball powers last met in the second round of the 2006 NCAA Tournament, with USC prevailing in three sets.
Sophomore Alexa Gray, who leads the Cougars with 3.91 kills per game, said they won't be intimidated.
"There are no more easy teams," said Gray, who received AVCA All-Pacific South Region honors this week. "You can't roll over anybody. You have to work hard for every ball. Everybody is good, so you have to outwork them and outplay them."
The Cougars are hoping that playing in front of 8,500 Hawaii fans at the Stan Sheriff Center got them ready to face USC's crowd, although it figures to be less than half as large. And BYU should have some strong support, with thousands of alumni and LDS Church members in the Los Angeles area.
"The crowd at Hawaii was unreal," Olmstead said. "But USC is a better opponent than Hawaii. I think the girls are up for it. It is kind of that mentality of, 'Why not? We just did it. Let's go there again.' I think they will take that confidence with them to Southern California."
Along with Gray, Olmstead said that middle blockers Kat LeCheminant and Whitney Young played well in Hawaii at the net, and sophomores Ciara Parker and Camry Godfrey were outstanding with their digs and passing. Junior Tambre Haddock, a transfer from Northern Colorado, also shined.
"Maybe our best performance, top to bottom, of the season," Olmstead said. "As a coach, it was almost a perfect volleyball match."
NCAA women's volleyball
P West Regional Semifinal Match, at the Galen Center, Los Angeles
8 p.m. • No. 21 BYU (24-6) vs. No. 6 USC (28-5)
Live Video • ESPN3