(written from a Production point of view)
McKenna worked several years as an assistant sound editor before she founded her own voice casting company. Among her earliest sound department credits are the comedy Exit to Eden (1994), Waterworld (1995), the western Wild Bill (1995), and Michael Bay's action thriller The Rock (1996). Beside her work behind the screen she voiced characters and was heard as background voices in films such as John Carpenter's horror film Ghosts of Mars (2001, with Joanna Cassidy), Marc Forster's drama Monster's Ball (2001), the drama Moonlight Mile (2002), the comedy Down with Love (2003), and the drama Bobby (2006). Also in 2006, she published her science fiction novel Logging Off. 
Beginning in 2000 she served as ADR Voice Casting Director on over 200 productions, including American Pie 2 (2001), Training Day (2001), Cameron Crowe's Vanilla Sky (2001), Scooby-Doo (2002), Steven Spielberg's Catch Me If You Can (2002), Daredevil (2003), Bryan Singer's X2 (2003, starring Patrick Stewart and Famke Janssen), Monster (2003), The Last Samurai (2003, written by John Logan), Dawn of the Dead (2004), Steven Spielberg's The Terminal (2004, with Zoe Saldana), I, Robot (2004), The Bourne Supremacy (2004), Elektra (2005), Spielberg's War of the Worlds (2005), Fantastic Four (2005), X-Men: The Last Stand (2006), 300 (2006), Pirates of the Caribbean: At World's End (2007), and Resident Evil: Extinction (2007).
McKenna previously worked as ADR Voice Casting Director for J.J. Abrams on his action sequel Mission: Impossible III (2006) and the television series Lost (2005-2006, starring Terry O'Quinn and Daniel Dae Kim).
More recent projects include the horror thriller The Strangers (2008), the animated comedy Space Chimps (2008), the horror thriller Case 39 (2009), the superhero film Hancock (2008), the comic adaptation Watchmen (2009, starring Jeffrey Dean Morgan, Stephen McHattie, and Matt Frewer), and Bryan Singer's drama Valkyrie (2008).