<p>Does anyone know how could I programatically disable/enable sleep mode on Windows Mobile?</p>

<p>Thanks!</p>

Probably by modifying the "System Power States" as
described here
(but in c#)
That article also describes a way to prevent the mobile device to sleep (which is not exactly what you may want), by calling the native function SystemIdleTimerReset() periodically (to prevent the device from powering down).