installing a blog folder in an invisible folder in public_html

I really need help. I’m trying to install WP2.3 to my site where I also have oscommerce. I’ve had osc running for over a year, and the catalog folder is in public_html, but it’s set up so it’s invisible, so when people go to my store, they just go to https://www.site.com, not https://www.site.com/catalog. I’m not sure exactly how that works — my webhost did something to set it up that way (it was beyond me).

I was running an older version of WP on a separate domain, but I decided I wanted to start over with a new blog on the same site as my store for a variety of reasons. When I uploaded my blog folder to public_html, however, I got a 404 error when I tried to go to the install page. I contacted my webhost and they said I needed to upload it to the catalog folder because that was functioning as my public_html in this case. Ok, so I did that, and did the install. But when I viewed the site, the links didn’t work. Comment, uncategorized, etc all give a 404. I asked the webhost again, and they said to put catalog in the address on the options page, but when I tried that I got another 404 error, this time for login.php. They couldn’t help me anymore and said to search the wordpress site, and I don’t even know what to search for. Is this something that can even be done or am I trying to do something impossible? I’ll be really grateful for any help!