Are you referring to the use of xsd:list?
Then as far as I know there is no way to do this because xsd:list is limited to simpleTypes, built-in, and derived types.
Here is some more information on this type including what built-in types are supported.
http://www.w3.org/TR/xmlschema-0/#ListDtAlso, out of curiousity, how do you want your content represented? Items in a list are usually something like:
<list>a b c</list>
How is your content type supposed to match this?
Hope this helps,
-jacobd