Is there any way to populate those fields ? perhaps in x-cart format ?
I am thinking of making a price update/ importer
At this moment the new bulk item pricing cannot be imported or set via API.
However we see this feature as a very important one. It will allow to create a lot of great tools that will import and sync products from different sources, update prices in the real-time, 3d-party services to manage your items and do batch updates.
So we are going to improve our import format significantly and extend our Product API by adding functions that update/create items. As usual no exact ETA yet
it is in our roadmap.