I am not getting idea to display Alerts in Mashups!
The description of your question is not very clear. Do you want to assess alert mashup? You can use URL http://localhost:8088/Thingworx/Runtime/index.html#master=ThingWorxMonitor&mashup=MonitoringAlertSummary
You also can embeded this page to your own mashup by below method:
Add a Contained Mashup widget and bind MonitoringAlertSummary to contained mashup.
If above two solution are not work for you. Please give us some detial informaion about your case.
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