CXLeverage is still buggy. It has two sets of menus, the first of which is not available when you first log in. You have to check an actual initerary, any itinerary, to get to the advanced menu.

Here's what to do.
1. Log in.
2. Check any flight on any day.
3. Ignore what comes up, notice the new menus.
4. Click Create New Itinerary
5. Click Multi City Search
6. Now it offers you to list your segments and whether they are by ground or by air and what class of service you want for each leg.