How to alter quote parsing?

I know there is a plugin for removing the fancy quotes. But I would rather like to alter them. I like the function, but since I write in Swedish I would like the same quotation mark on both sides of the quote: ”quote”. If I just had to change it manually in my own posts I wouldn’t bother, but I want the quotation marks to be correct in the comments posted by my readers to. (Since my blog is about the Swedish language, this is important to me.)

I was thinking this might be easy to fix, if I just could get some help to find the right part of the code. Perhaps I will need some other tips on the road too…

Thanks in advance