store all the animation names and animation speeds in arrays, then pass that to an animation_handler to control all anims

Code:
TEXT* txt_anim_names = {
   string("idle_start", "idle_loop", "idle_stop") //etc...
}

var anim_speed[30] = { 3, 2, 3.5 };

then just pass the anim number thro the handler and reference as needed
void anim_handler(int anim_type){
   animP += anim_speed[anim_type] * time_step;
   ent_animate(me, (txt_anim_name.pstring)[anim_type], animP, ANM_CYCLE);
}

btw, you're best off storing the animP as one of the entitys' skills
hope this helps

*tested, though written from memory*