Setting the min value on the x (category) axis to 0, rather than 1

I have a large data set of values that has a zero'th value (values
contained in a C-array). In previous versions of Excel, I seem to
remember being able to set the x-axis numeric values to start at 0,
and incrememt every so-and-so much. Now, with Excel 2008, I can't seem
to figure out a way to start the numeric values starting on the x-axis
at any value other than 1 (which in itself causes odd values to be
shown for any increment value other than 1, and when your array is
over 300 elements long...).

Can anyone provide a pointer on how to do this with the new version of
Excel?

Thanks!

--
Viktor Haag