I have work about 3+ years, I have developed several websites and software, all of those works are connected with eBay.
You want "eBay listing importer", it's import eBay items, or eBay order?
Following is my stpes:
1) put a button, named "Import eBay items", at user's dashboard
2) when user click this button, "Import eBay items using AJAX", after import over, show them to the page.