Easier than direct table editing, Developer now has built-in permissions editing. Check out the Permission button on the file properties.
Just right click on the file in the Components View and select properties. In there, you'll se a new button for Permissions. All of the well known group names (i.e. Users, Administrators, Backup Operators, etc) work, but keep in mind that the ACLs replace that is there, they are not additive.
To do the same for a folder, select the Destination Permissions elipsis (...) in the Component grid, when the component is selected.