Merging wordpress with site design programs.

Ok I have never had to post before and I have a few blogs but what I’m trying to do now has me stumped. I want to make my blog the homepage of my site but I want it to reside on the same root as a website made with php.
So for instance I want the side bar of the blog to point to links to the main site and also act as a landing page for my site. I have to keep the blog as close to the main site as possible. So subdomains won’t do. I have written my own theme with all the help from here and I thank you all. Also I use another designer that outputs php and it’s own htaccess file I looked all over the forum before posting like I normally do but I can’t seem to find anything like this. So the skinny of it. Install wordpress to public_html also install the site with it’s own htaccess file to to public_html and keep it spiderable. I guess maybe htaccess manipulation of some kind? I’m so at my wits end. Thanks for all your help.