Catalog hierarchy and iLife

I'm having a little trouble this morning wrapping my mind around the intended hierarchy of catalogs for use with instaup2date... specifically where the iLife installer would go. I get that you don't generally want to alter the "10.6_vanilla" and "iLife11_Updates" catalogs, so that you can just check out a new copy when new updates are released. So where would the iLife installer itself go - which catalog, and under what category? How do you structure the hierarchy so that it processes "10.6_vanilla," then the iLife installer, then "iLife 11_Updates"?