You can obtain a ScheduledJob instance through the static overload, passing in your type and assembly. When you have an instance you should be able to modify its parameters, and save it.

Something like this should set a schedule of daily at midnight, (note this is untested):

            var yourJobType = typeof(YourScheduledJob);
            var assemblyName = Assembly.GetAssembly(yourJobType).GetName().Name;

            var yourJob = ScheduledJob.Load("Execute", yourJobType.FullName, assemblyName);

            yourJob.IsEnabled = true;
            yourJob.IntervalType = ScheduledIntervalType.Days;
            yourJob.NextExecution = DateTime.Today.AddDays(1);
            yourJob.Save();

Hope this works for you.