Absolutely! This is exactly how I diffused my triggers (but my triggers didn't lead to SI). What I did was first identify what triggered me. Then I identified what was being triggered up from the past. After this the work only occurred when I got triggered again. When I got triggered I would remind myself of what was being triggered from the past and then reminded myself that this past wasn't occurring anymore and grounded myself in the present. After several rounds of this I actually diffused the trigger. It was like I rewired it in my brain. If it is a big trigger from the past it will need to be discussed in therapy so that you can release the emotions around it in therapy.

What I just discussed is a traditional trigger. SI triggers might or might not be different? My understanding of the SI trigger is that emotions get aroused and the SI diffuses or decreases the emotions. Further work on this might be expressing the emotions?

Maybe if you work through one here it will clear some of this ^ up? (And I do agree that this is a great place to work through many things, triggers included).