Try this:

define face_speed_x2, skill__;
define turn_speed, 2; // ?

Code:

---

//do the turning
vec_diff(face_pos,my.x,my.check_x);
vec_to_angle(face_ang, face_pos);
face_trn.pan = ang(my.pan - face_ang.pan);

if (face_trn.pan > 0)
{my.face_speed_x = min(my.face_speed_x + 10*time_step,  face_speed);}
if (face_trn.pan < 0)
{my.face_speed_x = max(my.face_speed_x - 10*time_step, -face_speed);}

my.face_speed_x2 += clamp(my.face_speed_x - my.face_speed_x, -turn_speed*time_step, turn_speed*time_step);
c_rotate(my,vector(my.face_speed_x*time_step,0,0),ignore_passable + ignore_passents + ignore_me + glide);

if (my.face_speed_x > 0) {my.face_speed_x = max(my.face_speed_x - time_step, 0);}
if (my.face_speed_x < 0) {my.face_speed_x = min(my.face_speed_x + time_step, 0);}

---

...Haven't tested it, but it should work. Just adjust the turn speed

And the textbox needs to be larger. I can't really read wwhat I reposted