I use an LDG AT-897 Plus auto-tuner, which is designed specifically for use with the 897/897D. Here is a quote from the manual regarding radio settings (it's a cut-and-paste):
"Turn on power to your transceiver. Once it powers up, hold in the FUNC key for one second to
access the extended menus. Rotate the SEL knob until menu #001, “EXT MENU” appears.
Rotate the dial knob until “ON” appears, to activate the extended menus. Rotate the SEL knob
until menu #019, “CAT RATE” appears. Rotate the dial knob until “4800” appears. Rotate the
SEL knob again until menu #020, “CAT/LIN/TUN” appears. Rotate the dial knob until “CAT”
appears. Hold the FUNC key for one second again to return to normal operation."
I don't know if the same applies with a different tuner.