ATC SWITCHED THE ILS TO THE OPPOSITE END OF THE RWY DURING DC10 ILS APCH CAUSING THEM TO HAVE ERRONEOUS GS READINGS AND GOING TOO LOW TOO SOON CAUSING AN ATC LOW ALT ALERT.

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FLT ACR X HNL-LAX ON MAY/XA/00. ON DSCNT; ATC ADVISED 'THERE WILL BE 1 OR 2 APCHS TO RWY 24R; THEN LAX WILL SWITCH AROUND TO RWY 6L FOR ARRS. EXPECT AN ILS RWY 24R.' WE INTERCEPTED THE LOC (108.5) TO RWY 24R AT APPROX 10 NM AT 2500 FT; AUTOPLT ON AND COUPLED TO THE LOC. CAPT'S ADI SHOWED WE WERE 2 DOTS HIGH ON THE GS. THE FO'S ADI HAD A GS FLAG. THE SO ALERTLY NOTED THE AURAL IDENT ON CAPT'S VHF NAV WAS DIFFERENT THAN FO. MEANWHILE; THE CAPT DSNDED TO 1500 FT TRYING TO INTERCEPT THE GS FROM ABOVE. AS IT BECAME APPARENT SOMETHING WAS CLRLY WRONG; THE CAPT LEVELED OFF THE ACFT AT 1500 FT MSL. WE QUERIED ATC ABOUT THE ILS SIGNAL AND THEY IMMEDIATELY RESPONDED THEY HAD A LOW ALT WARNING ON US (INSIDE ROMEN LOM). WE WERE ADVISED TO TURN TO 280 DEGS; CLB TO 3000 FT FOR AN ILS RWY 6R. SUPPLEMENTAL INFO FROM ACN 474597: AFTER LNDG ON RWY 6L WE ASKED THE LAX TWR CTLR 'WHAT HAPPENED? DID YOU CHANGE THE FREQ TOO SOON?' (MEANING CHANGE THE ARPT AROUND FROM A W LNDG OP TO AN E LNDG OP.) 'YEAH;' HE SAID. 'THAT'S WHAT HAPPENED.' APPARENTLY WE HAD INTERCEPTED A BACK COURSE FROM RWY 6L ON APCH TO RWY 24R. OUR DIFFERENT GS INDICATIONS AND GETTING DIFFERENT FREQ IDENTS ARE MORE DIFFICULT TO UNDERSTAND.