Developer forum

HI Ben,
you can use the Ecom provier as a destination and provide the mappings/source values for the "EcomProductCategoryFieldValue" table:
columns: FieldValueProductId/FieldValueProductNumber should have some value to assiciate it with product
FieldValueFieldId - should be your existing category field id, so it is needed to have the category and its fields being created before importing the values to this table,
FieldValueValue - field value.

As an options you can write the code to create the ProductCategory and populate it with fields directly in your source provider:
public override void LoadSettings(Job job) method
using this code:

var category = Ecommerce.Products.Categories.Category.GetCategoryById(categoryId);
            if (category == null)
            {
                category = Ecommerce.Products.Categories.Category.Create(categoryId);
            }

            var categoryField = category.Fields.GetFieldById(id);
            if (categoryField != null)
            {
                categoryField.Label = label;                
            }
            else
            {
                category.AddField(id, label, templateTag, typeId,
                    string.Empty, FieldListPresentationType.RadioButtonList, new FieldOptionCollection());
            }
            category.Save();

Regards,
Dmitrij