Someone has posted an excellent guide on how to do this on the steam forums
Summarized here:
Edit your bioinput.ini file and put these commands under the bindings section (bioinput.ini > sfxgame > sfxgamemodebase > bindings ):
( Name="NumPadZero", Command="FOV 32" )
( Name="NumPadOne", Command="FOV 0" )
( Name="NumPadTwo", Command="FOV 75" )
( Name="NumPadThree", Command="FOV 80" )
( Name="NumPadFour", Command="FOV 85" )
( Name="NumPadFive", Command="FOV 90" )
( Name="NumPadSix", Command="FOV 95" )
( Name="NumPadSeven", Command="FOV 100" )
( Name="NumPadEight", Command="FOV 105" )
( Name="NumPadNine", Command="FOV 110" )
You can add as many as you want but these will allow you to adjust FOV in game.