I've found that I have to put in each one manually, i.e. for each 4-week period, create a one-time assignment starting on the Tuesday of the start of the period and ending on the Monday at the end of the period, then check the "All Day" box. Set the Group and User dropdowns as appropriate. Repeat this process for each group member and for each period, as far into the future as you know the schedule. Don't use the "Recurring assignment" feature.
There's really no way to do it with logic like you would a recurring appointment in, say, Outlook.