Ok, disregard that last one... I played around and figured it out:
Sub ChangeAxis()
With Charts("Chart1"

.Axes(xlPrimary)
.MinimumScale = Worksheets("Sheet1"

.Range("A1"

.MaximumScale = Worksheets("Sheet1"

.Range("A2"

End With
With Charts("Chart1"

.Axes(xlSecondary)
.MinimumScale = Worksheets("Sheet1"

.Range("A3"

.MaximumScale = Worksheets("Sheet1"

.Range("A4"

End With
End Sub
xlPrimary changes the x-axis and xlSecondary changes the y-axis. (so Xmin = A1, Xmax = A2, Ymin = A3, and Ymax = A4)
I wasn't able to run the macro unless the chart was in it's own sheet, but I'm sure that's just a matter of referencing it correctly. (If you haven't already noticed, I haven't ever done this before).
Anyway, I hope this helps!
Jproj