New User welcome to the forum. The time delay limit at the moment is infact 4-1/2 hours. It looks like X10 programmers maybe making some changes to the software in the hopefully near future and maybe the time limit will be extended.
Until then you might try this...
Note I have not tested this but it should work. Create 1 macro to turn on your light and dim it to 1%. Set a time delay to 4 hours and then have the macro turn on a dummy module after the 4 hours. Create a second macro that has the same House/Unit code as the dummy module in the first macro. This second macro will be triggered when the first macro finishes. Set a time delay in the second macro for 4 hours then finish it with the commands to brighten your light.
(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)----KDR