How to make a T pose into A pose

I have a mesh made in Maya and I even have it use the Epic skeleton for major bone names (except for eyes and other misc). I want to put it in the market place but it needs to also be in A pose.
I cannot find out what the A pose entails as changes from the T pose. Clearly, the arms are lowered and the forarms also rotated while the legs also move.
However, by how much?

Is there a quick and dirty way to just retarget it?

You can import the UE4 mannequin into Maya and check the proportions. There is a quick video showing the workflow of a marketplace asset developer.
HOW TO MAKE EPIC SKELETON IN MAYA FOR UE4 WITHOUT PLUGINS - YouTube

So here’s the solution.
Make a POSE asset and change the pose or retarget it to another if you have one handy.