looking like you would need something like

Code:
ent.pan -= sign(ang(180 + ent.pan - targ_vec.x)) * 5 * time_step;
ent.tilt -= sign(ang(45 + ent.tilt - targ_vec.y)) * 5 * time_step;
ent.roll -= sign(ang(180 + ent.roll - targ_vec.z)) * 5 * time_step;

untested

play with 45 in tilt as it changes from -90 to 90... mmm, 0 is also a variant wink

1st prize: Lite-C and Newton 2.17 by Vasilenko Vitaliy

Newton2 videos: http://tinyurl.com/NewtonVideos
LiteC+Newton2 discussion: http://tinyurl.com/NewtonWrapperDiscussion
Latest LiteC+Newton2 version(v23, from 29.10.2009): http://depositfiles.com/files/ae1l0tpro