I have the ability to change the API keys when creating items, but I don't have that ability in the Customs Table section. My only option right now is to delete the table and re-create it. Not a huge deal but a nice to have.
This is possible today. In the API, Custom Tables are referred to as Custom Objects.
Here's a link for more information: http://www.aha.io/api/resources/custom_object_records