How do I set up international shipping for Shopify Managed Markets via my fulfillment center?

[jamielenore]

I am integrated with my fulfillment center's WMS through Extensiv. The fulfillment center uses TechShip for shipping. 

This works seamlessly for domestic orders. However, I recently set up Shopify Managed Markets and can't find the proper information online or via chat on how to integrate these international orders into this flow. 

What do I need to do/tell the fulfillment center to do? 

From what I can find, there is only information on how to print international Shopify Managed Markets labels directly in Shopify, or how to trigger an order fulfillment email to the fulfillment center, which is not sufficient.