Hi,
If you're referring to custom pages in the AdminCP -> Pages tab, this is possible in both version 1 and version 2 by editing the custom page, where a permissions section will appear :)
Unfortunately, in version 1, all users will be able to see the link regardless of whether they can view the page or not; this has been fixed in version 2 (which is still in pre-release stage and will hopefully be released soon).