You still need japanese locale even if its the english version. I dont recomend applocale, its better to just change the whole system locale.
When you say patch do you mean a txt document that modifies the files after downloading the program or something? Because you shouldn't need that if you downloaded the program from the right site. If you did download from the right site you should click the version with an little "e" next to the version number.
EDIT Here's the link to the site
Basically what Hulder said. If you have a modern computer (aka, anything beyond Windows XP), then applocale is unnecessary (you won't even be able to find it from Microsoft anymore; it's a practice so out of date). Change your System Locale to Japanese. You'll have less errors (bad number, mojibake, and other quirks that can happen running a non-unicode machine) and you'll be able to use more than just western made CV banks (if they're romaji encoded) or CVVC English. The official site has the latest version which includes a (mostly) English interface.
The program doesn't need the keyboard change to work. But you need it if you're gonna edit notes and make aliases for japanese banks. So if you're just gonna use banks that are not japanese, then no you don't need to install japanese keyboard settings.