Category as child of template

Hello,
I’m really stuck on something that is not have to be too difficult I think… I have various custom post types with categories. Now, I want these custom posts to be a child of a specific page.
Here’s an example:

What I have now:
http://www.mysite.com/article/post-name

I want this to be:
http://www.mysite.com/somepage/anotherpage/article/post-name/

How is this posible? I have my permalinks set up like this: /%category%/%postname%/.
Do I have to change something in my .htaccess file?

Thanks in advance!