I would imagine if you create a dataProvider with the desired time increments it should display fine. There was a forum post recently about how to generate a range of date strings, like 9:00, 9:15, 9:30, etc. I would search for that and then see the Flex Builder help sys on charts, and more specifically setting axislabels.
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Greg Lafrance - Flex 2 and 3 ACE certified
Flex / AIR Development, Training, and Support Services
Thanks, but I solved it already using the DateTimeAxis.
<mx:DateTimeAxis id="ca" autoAdjust="true" dataUnits="hours" parseFunction="dateParseFunction" displayLocalTime="true"/>