Hi,
There are many fields that ebay offers for us to include in our download, im not sure exactly which would match the "custom label" description you gave.
If it is SKU, we are currently downloading that. It is probably hidden from your default view. If you are unsure about how to hide and unhide the columns, let me know and I will guide you to a tutorial.
If that is not the field you seek, there are lots of extra fields that we included that are for the user to put whatever data they want in. They are also hidden by default.
Let me know if you need further assistance.