How to customize the Customer Portal Back Button URL with the SDK?

[vacom]

I'm looking for documentation on how to programmatically set the back button URL. When we receive the subscription, we obtain the URL for things like the Customer Portal, etc. While it's possible to do it in the Designer on the dashboard, this presents a blocker because we have different environment URLs. It would be ideal to redirect back to the correct place dynamically.

Any ideas? Thanks