The current way to set up FBO and/or intermediary bank for domestic wires is by clicking on "Additional Payment Information."
Ideally, it would be best for this information to come up on the Payments page automatically, if the Domestic Wire payment method is selected (just like with international wires).
If that is not possible, it would less confusing this clickable link would describe what it represents, instead of “Additional Payment Information," such as “Domestic Wires - For the Benefit of/ Intermediary Bank Account Information."