Given that there are only 20,000 OPC communicants in America, presumably all you need to do is show up on Sunday and introduce yourself to the elders.
I'm sure they'd love to have you.
Another good bet is to move to the Northeast if you don't live there already - that's the area of the country where you have the best shot of living within driving distance of a congregation.
**What would a baptized and confirmed Roman Catholic need to do in order to join the Orthodox Presbyterian Church?**
They actually are still a Catholic. Just not a practicing one.
We pray these people back into the One, Holy, Catholic and Apostolic Church!