Sorry, this is the highest resolution I could find (BYU has apparently scrubbed the previous matrices from their site). The minimum ACT score to get a half-tuition, two-semester scholarship was 32; to get a full-tuition, two-semester scholarship, a 34 or higher was needed; a four-year full-tuition scholarship required a 35 or a 36 on the ACT and a good high school GPA.
Here's a quote about scholarships this year:
In the past we have posted the academic cutoffs for incoming freshmen. This practice has been discontinued as it is too difficult to predict the academic performance and ACT/SAT scores of the incoming freshmen class.
All this applies to incoming freshmen; there are different criteria for continuing students.