Open file includes/gacl.class.php and add below line 162 (after the comment “add additional components for a manager as desired, or give access to all“) the following code:

$this->_mos_add_acl( 'administration', 'config', 'users', 'manager', null, null );
$this->_mos_add_acl( 'administration', 'edit', 'users', 'manager', 'components','com_checkin');

As a side effect, this will also enable other menus such as Site (with configuration’s options) and Messages.

If you want to show only a Global Checkin menu item you should modify the full menu module in administrator/modules/mod_fullmenu.php by editing line 35 from:

$canConfig = $acl->acl_check( 'administration', 'config', 'users', $usertype );

to:

$canConfig = (bool) ($acl->acl_check( 'administration', 'config', 'users', $usertype ) && strpos($usertype,"Administrator") !== false );

Then add at about line 303 (there’s a closing curly bracket ):

if ($usertype == 'Manager') {
?>
     [null, 'Global Checkin', 'index2.php?option=com_checkin', null,'Check-in all checked-out items'],
<?php
}

Note: On some installations or different versions of 1.0x lines can differ.

————————————-

03/02/09 UPDATE: I’ve zipped the hacked files to make it simpler to patch your installation. Note that these files belong to a english Joomla 1.0.13 clean install. You can browse change with a compare software like WinMerge.

To overcome this problem, users usually rely on an (super) administrator user action, since it’s the only user level who can access the Global Chek-in tool in the backend panel.

The main concern in this ACL rule on Joomla is that most of the times users who manage the website contents have a manager access level, since this user level is much more restricted on technical configuration’s options.

To allow Global Check-in action for managers, just edit the core file located at /libraries/joomla/users/authorization.php adding below line 91 the following code:

$this->addACL( "com_checkin", "manage", "users", "manager" );

Important: Since this is a core hack, keep in mind that it could be overwritten on further upgrades!