The MIDIOutputEvent Sound outputs pitch bend continuously as the Frequency parameter value changes. The range for the pitch bend output is 12 nn, so you could use:
60 nn + ((!LocalTime gt: 0.001) * !YourOutputValueInRangeOfPlusOrMinusOne * 12 nn)
in the Frequency field and
!LocalTime
in the Gate field. This will cause the MIDIOutputEvent to initially send a key down with 60 nn and then, after the first millisecond, it will output the EventValue using pitch bend messages.
You could use the simpler expression
60 nn + (!YourOutputValueInRangeOfPlusOrMinusOne * 12 nn)
in the Frequency field if you can be sure that !YourOutputValueInRangeOfPlusOrMinusOne will be zero when your Sound starts.