customize look of phpbb

I have a phpbb 2.x forum on my current site. I need to intergrate it into my current site so that it looks like its just another page on my site. You can't use new theme files. You have to use the existing subsilver theme. The link to the site is [login to view URL] and I want the actual forum look to not look like a forum. Not very difficult for you phpbb gurus out their.