I know the first two will join the team (at least once classes begin) but I'm not sure if the rest of these will join/re-join the team. I show them as "additional possibilities":

Adam Hogan, FC, http://byuroster.com/2012/05/29/interview-with-new-walk-on-cb-adam-hogan/
Daniel Lacey, likely DB, http://byuroster.com/2012/04/13/new-walk-on-this-fall/
Blake Morgan, FS (RM), http://byucougars.com/athlete/m-football/blake-morgan
Connor Whitlock, FS (RM), http://byucougars.com/athlete/m-football/connor-whitlock
Ryan Comer, FS, currently enrolled at BYU, not sure if he will return to the team, http://byucougars.com/athlete/m-football/ryan-comer
Mike Wadsworth, FS (Transfer from Hawaii, will sit out 2012, can walk on in 2013)
Drew Reilly, SS (Transfer from CSU, will sit out 2012, then scholarship in 2013- 3 years to play 3)