Hi Steve, I often use the Max Hold trace type. I set one trace to Max Hold and the other to Clear Write so that I can see what is going on. You can also use the single in the Sweep/Trig menu, but it could be hard to time it right to capture the desired signal popping up. After the Max Hold grabs the shot you want, you can change the trace type to Freeze and it will hold it there without subsequent traces influencing the capture. Go to the Trace/P/F menu and select the Tace Type there.
Hope that helps.
Len