hi,
I guess you want to animate the entity and then smoothly animate back to its start position, isn't it?

In that case you can use cosine function for the animation percent.

Code:
var nAngle = 0;
while ( nAngle < 360 )
{
   ent_animate ( me, "Take", 50 - fcos ( nAngle, 50 ), NULL );
   nAngle += time_step * 30;
   wait(1);
}