- Navigate to System > System Settings
- Select TinyMCE from the dropdown filter
- Under the General Area add table to the value of tiny.custom_plugin
- Under the Custom Buttons Area add tablecontrols to the value of tiny.custom_buttons3
Update 11 March 2013: TinyMCE is not available in MODX Revolution 2.2.2, instead search for tiny.custom_plugin and add table to its value, then search tiny.custom_buttons3 and add tablecontrols to its value.
Screenshots from MODX Revolution 2.1.1-pl.
More information in the MODX Documentation at: http://rtfm.modx.com/display/ADDON/TinyMCE.Table+controls