Help! seeking and changing only part of URL

Hi,
I have a question about my site…
I have to set button for changing the default language with another one … this button have to be in my flash header … only the header in my site is flash …
How can I do this … ?
I want to read the current URL and change the part of it …
for example:
www . myweb.com/en/about.html
>>>> www . myweb.com/fr/about.html

Is this possible with ActionScript 2.0???
Sorry about the question … but I really need the answer!!!

Thanks a lot!!