Is it possible to use stringoverride on ONLY one page? I want to modify ubercarts "Add to cart" text button but only on ONE page that I've customized. I haven't been able to figure out how to call the button via php so I don't know if that's possible. I figured I could use string override but that would change the text across all pages and for that I can just change the option in ubercart.
I'm betting you're looking for hook_form_alter() ... I'm pretty sure its just a form buttom on the page and you can change its #valueproperty as-needed with that hook. Its up to you to figure out how to target just that form, on just that page ... I don't think you need stringoverride for this.

You would want to test this out of course :)