Okay, so I made a workaround by duplicating the layer and changing the anchor point, but this seems like kind of a weird workaround, and I feel like somehow probably knows a better way.
p.s. Do you guys ever have moments working with AE where you are like, "This program rocks."?
The first question I have is why do you want to do that?
If you're doing a rotation or scale around the anchor point and you want to change the axis as the animation proceeds then I could possibly understand, but this is kind of a wonky workflow to me.
Be that as it may, try adding this expression to your position value:
apAdjust = anchorPoint - [width, height]/2; value + apAdjust
Changing the anchor point will now now not change the position of the layer. This will work for 3D and 2D layers.
What Rick said. It's a pretty atrocious workflow. You better learn the fine art of building hierarchies using parenting for this kind of stuff...
Can you be more specific please, Mylenium? I'm interested in creating as clean workflows as possible, so this could be a learning opportunity for me.
Thank you Mr. Gerard for the expression.