I'm not sure I understand you fully.
You side chain an audio signal to OSC 1 in Ultrabeat to trigger a sound.
You create a sequence in the step sequencer in UB for that voice.
When playing back the sequence in Logic, you can hear the audio part triggering the voice?
Drag the pattern to the Arrange and switch off UB's sequence (power button).
Play the region in Logic and you will hear the side chained audio being triggered as long as that audio region is also in the Arrange too at.
e.g. if your UB region starts at Bar 1 and finishes at bar 17 and the audio region (the sidechain trigger) starts at Bar 9 and finishes at Bar 17 you will only hear the sidechain voice betwen bars 9-17.
Sidechaining is a realtime process...
Let me know if that helps (or not)...