You could use a set data value extension to add an s.event.
Let's say that you have a data source called "sc_events", then when you add your Set Data Value extension:
1. Select "sc_events" from the drop down
2. Change the "To" drop down to "JS Code"
3. Your code will be something like
4. Set the condition to "url contains selectSessions"
5. Scope the extension to your SiteCatalyst tag
For more detail see this post on the SiteCatalyst tag: https://community.tealiumiq.com/posts/548398 or contact your Account Manager for more 1-1 support.
Not sure exactly what "u" represents but my understanding is the u.addEvent is a function built by Tealium within the SiteCatalyst Template and adds the event values to the s.events object automatically.
Also, you may want to change your data object of sc1_events to simply sc_events as Clint mentioned. sc_events should automatically capture the event(s) with no additional mappings needed within the tag.
"u" is the local object for each tag that contains all the utility functions and data for that specific tag.
So in order for the u.addEvent function to work you will need to scope the extension to the SiteCatalyst tag because the addEvent function will only be available within the SC tag template.