Hot do i rewrite links?

[vituocgia]

I'm using Vietnamese language, and i want to know how do i use friendly link without any problem like this it's : http://diendan.nhinxem.net/links/mng-giao-thng-2/ => the correct which i need is http://diendan.nhinxem.net/links/mang-giao-thuong-2/ ( the text at category name is : Mạng giao thương!
I think we need to convert special text ( vietnamese ) to ascii text. But i dont know how to do this...
Plz help me!
Thanks

[Brian]

Currently only English characters can be converted, though there may be some hacks that would help if you search the forums here.