What you described doesn't seem to require involvement from actual titular
scripted_sequences. You just need
multi_managers choreographing the triggering of other things in a precise manner.
But to cover both bases, model sequences do have a specific event that fires triggers, which you can rename entities to match and get triggered with. Refer to
https://the303.org/tutorials/gold_qc.htm#A1, specifically at event #1003. This is how Barney at the reception desk of Sector C swivels on his chair back and forth. So to use it in your map, you can review the model's sequence in HLAM and look for event #1003 (or even add one yourself).