You can't. Before '96 the cars were not ODB II, so no interface for the Solo DL2.
Even the '99 with ODB II, the refresh rate on the ODB II port is too slow to provide any useful data, 1 hz. It's fast enough to diagnose engine issues, but not for track data.
The '06 NC ODB II is the first to provide useful data.
The only way to get the data is to upgrade to at least an MXM and get the proper sensors. There are many vendors familiar with the right sensors for a Miata, X-Factor, Advance Autosports.
All it takes is significant money.