root is the super-user, and as super-user, root can make ANY change... so you shouldn't have to switch to any other user to configure lilo.
/etc/lilo.conf is a configuration file; it contains lilo's settings and nothing more. From your post, it sounds like you tried to run it (by just typing /etc/lilo.conf), and, since lilo.conf isn't, and shouldn't be, executable, the "Permission denied" error resulted from the executable permission bits not being set.
You need to edit the file, not run it. Some distributions come with a lilo configuration program that makes this process easier, but I'm not sure what that would be with Mandrake. If you have documentation, as is highly likely, I suggest you check it. Configuring lilo is something that would be there.
Last edited by zhangmaike; 07-04-2005 at 02:38 PM.