Ok, you have a couple options.
1) Open the kX DSP Window and connect the output of the timbre plugin to the Center and LFE inputs of epilog, and connect your speakers to the Center/LFE/Digital jack on the card (the one the furthest away from the joystick port).
2) This one requires kX version 3538h. Go
here and download one of my SB022x test plugins. Unload epilog, and load the test plugin. Connect timbre to the Analog Rear connections of the test plugin, and plug your speakers into the jack on the sound card for the rear speakers (the one closest to the joystick port).
When the next version of kX is released, the "Swap Front and Rear" option should work for you.