I know I did this before: created an output class to remove the indent from simple lists within tables. I want to do this at the list level, not the list item level, but i can't find any settings where something like [SimpleList] uses the [SimpleListItem]. I want to override it with a custom [SimpleTableList] that uses [SimpleTableListItem] with left margin set to 0, but I can't figure out how to specify that my new list uses my new list item...
Setting formats
It sounds like you need (in your d2*.ini) something like:
[BlockFormatMaps]
; this handles simplelist in a table cell
sli/sl/entry/*=SimpleTableListItem
sl/entry/*=SimpleTableList
; and this does it for a simpletable cell
sli/sl/stentry/*=SimpleTableListItem
sl/stentry/*=SimpleTableList
Then set the format's margin left. Or padding.
HTH!