You don't really. The drive itself reports it's native operating mode.
In XP, certain devices have error counters. When a device logs a
certain # of errors XP decreases the operating mode to attempt to
stop the error(s). First you need to ensure that your BIOS detection
is correct for the optical. In other words that it is set to Auto and
that no manual settings are in place. Once Windows is running you
can open the ATAPI/IDE controllers category in Device Manager
and then expand the host controller (Pri/Sec). Most recent drivers
have an Advanced (TAB) that shows the device's operating mode.
Some have a Toggle for Transfer mode where you can pick DMA
or PIO. The "Workaround" solution for step-back issues is to just
uninstall the device & it's controller and then re-boot. However if
errors continue XP will again reduce the optical drive's operating
mode.
