If you want the origin from which the player is looking, just add the EV_VEC_view_ofs to EV_VEC_origin of the player.
Code:
new Float:viewofs[3], Float:origin[3]
entity_get_vector( id, EV_VEC_view_ofs, viewofs )
entity_get_vector( id, EV_VEC_view_ofs origin )
//even though only one axis is effected, its just good habit to do them all ;)
origin[0] += viewofs[0]
origin[1] += viewofs[1]
origin[2] += viewofs[2]