Though no official support has been added to the manager interface, you can add the following to the {table_prefix}system_settings table to make the nodes visible even if the user does not have permission to that node:
[table]
[tr][td]
setting_name[/td][td]
setting_value
[/td][/tr]
[tr][td]tree_show_protected [/td][td]
1
[/td][/tr]
[/table]
Here is a SQL statement you can execute (in phpMyAdmin or from mysql command line) to add (or update) the record.
REPLACE INTO `{table_prefix}system_settings` (`setting_name`, `setting_value`) VALUES ('tree_show_protected', '1');
NOTE: Be sure to replace {table_prefix} with the actual table_prefix you used to install MODx, e.g. modx_, and refresh your site cache after adding this setting. This only works in version 0.9.6 or later.