i am guessing you are trying to do a dynamic display?

if that is the case i would use different controls for it. Several third party list controls that are built to specifically support this case (load items dynamically from webservice as user scrolls)

if you want to play with the weblist i have not looked but i am pretty sure what you want is not available on the flex side so you could take a look at the WebListModel/WebListPagedModel and WebListScrollingView js classes as well as the WebList js class