I had a look into this, and it looks like it's done through the calendar, for what you want, you would need to:
1) Create an event type for shifts
2) Set the event types to "agents not available"
4) Create a recurring daily event in the hours that the agent will NOT be available for each shift, then assign the teams to the events.
You'd need two "events", one for each shift.
Shifts seems like something that would be easy enough to implement separately from the calendar, might need to ask Lansweeper nicely. 😛