How and where do I mail documents to the IRS about a stock sale when the foreign broker refuses to provide a 1099-B?

You will need to mail copies of your brokerage info along with a form 8453, Transmittal form to:

 

Internal Revenue Service

Attn: Shipping and Receiving, 0254 

Receipt and Control Branch 

 

Austin, TX 73344-0254

 

Here is a link with more information on the topic.

 

You can find a form 8453 here.  You'll check the "8949" box near the bottom of this form.