Always scale layer from comp center (not layer anchor point)

Usually if I want to scale a layer from any place other than it's center, there are two ways I do it:

1) Parent that layer to a null, then scale that null. (which is workable, but it adds another layer and prevents the layer from having an other direct parent)

2) Adjust the anchor point. (which is difficult when the layer is already animated and you need to keep everything in place)

So both ways are kind of a hassle and neither are perfect.

Is there any expression magic that would always scale a layer from the comp's center?  What would be super cool -- an expression checkbox where I can switch between scaling using the Comp Center <-> Layer Anchor Point.

But I'll take what I can get