This feature is accessible by adding a new connection, a source step or a destination step that connects to Oracle NetSuite SuiteTalk.
The below page is where you will fill your NetSuite SuiteTalk credentials to establish a connection. This page is accessible by creating a connection in the solution or by creating a connection in the source or destination step.
The below link assists with creating the credentials:
NetSuite Applications Suite - Token-based Authentication and Web Services
Illustrated below is an image of the source step. To add a connection, click on the highlighted icon. The Route field is where you will type out the API and exclude the host.
Below is the link to the API references to use: