How do you make leveled item lists in SSE Edit (for multiple outfits to be distributed by SPID)?

[Dr.Modz]

I know how to make outfits in SSE Edit, but I have no idea how you would go about making outfits into leveled items that can then be combined into a single outfit that SPID distributes one of. I've seen various mods that use that technique, but I cannot find a single tutorial online on how to even start doing it. Help would be appreciated!