One approach might be to use the StepSequencer with each of its parameter fields set to an array of EventValues that is the maximum length of any you plan to send. Then you could send an additional EventValue to set the EndIndex of the StepSequencer, thus playing only the first n stages of the sequence (where n is the length of the array of values you just sent).
For example, assume a maximum length Array of 16. Then you could set the StepSequencer fields to:
KeyPitches: {1 to: 16 collect: [:i | !p suffix2: i]}
and similarly for any of the other fields you'd like to control. In the EndIndex field you could put:
!Length - 1
Then for example, if you had an array of three pitches, you would send them as !P01 !P02 !P03 and you would send a value of 3 for !Length.
If you want the sequence to repeat, check the Loop box. Otherwise, you could set the Gate field to another EventValue and sent it a value of 1 to start the sequence.