I already have thousands of post and a specific theme, I don't want to change all that...

Hi, I srsly can't install phpSEO mod... it's making me sick :'( I've downloaded almost all version downloadable on the site, but there is no documentation, no installation information on the forum, in the .txt file, they said I had to replace all the phpBB files -_-, (it was the premod I guess), the...