I have a spreadsheet that tracks certain events that can occur within
hours of each other, or within a couple of days.  I need to chart this
data on a realistic timescale, so that events that occurred within a
few hours of each other will appear to be physically closer on the
graph than two events that occurred two days apart.

The online help in Excel tells me that I "can't create time-scale
charts from data that is measured at intervals of hours, minutes, or
seconds. Only days, months, and years are considered base units in
time-scale charts."  Therefore, I'm trying to re-invent the X-axis of
my chart so that it represents a timescale appropriate to my data.

Any ideas out there on how to approach this?  Thanks.