Thanks for your question. Yes, this is possible with FAB 3000 and typically can be achieved in a few minutes.
Here's the 5 steps, and I'll then provide a complete demonstration tutorial movie:
1 Import Gerber/Drill/Netlist file using AutoLoad (menu: File / Import / AutoLoad...)
2 Assign Layer Types (if not already detected by FAB 3000).
Note: Typically the netlist already contains the Components information, so XY file are not needed. If you do wish to import an XY centroid file and use it, here's a dedicated forum post to that task:
3 Do you wish to have have components? If yes, here's how to generate from Netlist file: http://www.numericalinnovations.com/blogs/news/how-to-generate-a-centroid-file-aka-pick-and-place-for-any-pcb-in-less-than-2-minutes
4 Do you wish to have Nets in the ODB++? If yes than perform the following to extract netlist from the Gerbers (which do not have any net info): https://numericalinnovations.freshdesk.com/support/discussions/topics/14000002413
5 Export ODB++ file. Go to menu: File / Export / ODB++, and select the location where you wish to save the ODB++.
I am importing a sample set of Gerber files, Drill file, and IPC netlist file. Performing the steps above, and then export to ODB++. Lastly I use the Valor ODB++ Viewer for visual verification.
Here's the tutorial move:
Let me know if this helps.