ListLevel.Alignment (Word)

Returns or sets a WdListLevelAlignment constant that represents the alignment for the list level of the list template. Possible return values are wdListLevelAlignCenter - Center-aligned, wdListLevelAlignLeft - Left-aligned, wdListLevelAlignRight - Right-aligned.

ActiveDocument.ListTemplates(1).ListLevels(1).Alignment = wdListLevelAlignCenter