I was pleased to discover that the MicroLogix 1200 and the newer firmware PanelViews can use and display the "Long Integer" data type. This is a 32-bit signed number instead of the traditional SLC/MicroLogix 16-bit signed numbers, so it can have a value up to 2,147,483,647 instead of just 32,767.
The timer/counter methods suggested above are excellent ways to get a traditional "hour/tenths" meter, and the PanelView display can be simplified by directly viewing a six-digit integer. You'll define the PanelView tag as a "DINT" data type.
I think you can even define a DINT data type in PanelView and address it to a regular old Integer "N" file... it uses the next Integer element as the high word. You'd have to manually create the 32-bit value in ladder logic, but it would display as one element on the PanelView.