This requires some slight modifications of SMF's files:
In Sources/ManagePermissions.php, find:
'shop_trade' => false,
Add after:
'shop_admin' => false,
In Themes/default/languages/ManagePermissions.english.php, find:
$txt['permissionname_shop_trade'] = 'Trade Centre';
Add after:
$txt['permissionname_shop_admin'] = 'Shop Administration';
Then go to Admin Panel → Permissions, click Modify next to Global Moderators, and tick the "Shop Administration" box. This should work, but I've not tested it.