What is the best way to set up an international contractor in quickbooks. (Contractors aren't in the US and don't have any W9 information)

I have a way on how you can set up the contractor, CoachKeegs.

You can add them as a vendor. To add currency on how you pay the contractor, you can turn on the Multicurrency feature. Note: Once the Multicurrency is enabled, you can no longer change the home currency and turn it off. 

I've got this article for more details: Turn on and use multicurrency.

Then, follow these steps to turn on Multicurrency:

1. Go to the Gear > Account and settings.
2. On the left panel, select Advanced.
3. Scroll down to Currency, and choose your Home Currency from the drop-down list.
4. Click the toggle icon to enable Multicurrency.
5. Put a check mark on the I understand I can't undo Multicurrency box.
6. Click Save and then Done.

Please see this sample screenshot:

Once done, let's go add the contractor in the Vendors page.

Here's how:

1. On the left panel, click Expenses > Vendors.
2. Click the New vendor button located in the upper right corner.
3. In the Vendor Information window, add the contractor's information.
4. Select the currency from the I pay this vendor with drop-down menu.
5. Click Save.

I'm adding this article for reference: Add a vendor with a foreign currency in QuickBooks Online.

If you have other concerns with QuickBooks Online, please let me know in the comments below. Thanks.