I think its a complete DIY solution. Biggist pro/con this time is its mainly in the includes so not quite as straightforward to track down the currency. Plus side is that you only should need to change them once and it should be ok for all skins as they use the includes.
The worst is finding all the changes inside the charts and any JS currency.
I still stand by my original thoughts as of PS3 at the very least there should have been several download versions of PS in different currencies. The programmers will not a lot easier where all these changes should be made and surely wouldn't take too long to convert for us.
Anyway, I will attempt it as soon as I find the time just a pity its not easy for all customers.
I think WA doa fine job with their extensions but massivly fail with PS non-us support.