Yes, it is possible.
Actually, you were right, the Step buttons in Trig mode are used for this purpose. However, it depends on how the specific program has been patched.
Each of the 3 sub-sequences have 3 outputs: the sequencer output (step values), the trigger output and the accent output.
For instance, try Factory Preset #0001 and select Seq 1, you will notice that the Step buttons in Trig mode allow you to trigger or not trigger each step.
In Slide mode, the Step buttons allow you to enable/disable slide between the selected steps.
Finally, for each sub-sequence, you can adjust the length of the steps (and the speed of the slides), so if you turn this length parameter down, the steps will play staccato instead of legato.