That would only be possible using Shopify Scripts, which is only available on Shopify Plus.
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Scripts can be quite complex and difficult to navigate if you're not too familiar, so if you are thinking of moving to the Plus plan to do this, I would strongly suggested talking to @ThomasBorowski or another Shopify Expert in advance to make sure you know about everything before diving in.
Outside of that, once you have a live gateway on your store, it's possible for any customer to checkout using it if it's available to them in their region.