GND CONFLICT DURING AN UNCOORDINATED RWY ENTRY AT A NON TWR ARPT UNICOM.

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I WAS FLYING A BEECH BARON 55 WITH AN FAA APPROVED EXAMINER ON BOARD AS PART OF MY INST RATING TEST. I WAS INSTRUCTED TO FLY AN ILS RWY 9 APCH AT DADE/COLLIER ARPT. THROUGH UNICOM THE EXAMINER ADVISED TFC ABOUT OUR POS. AFTER LNDG I TAXIED BACK TO RWY 9 ON THE TXWY. DURING TAXI I INFORMED TFC VIA UNICOM THAT I WAS TAXIING BACK TO RWY 9 FOR TKOF. BEFORE LEAVING THE TXWY; THE EXAMINER AGAIN INFORMED TFC VIA UNICOM THAT 'BARON XX WILL TKOF OF RWY 9 AT DADE/COLLIER.' NO OTHER INFO WAS GIVEN THROUGH UNICOM. WHILE TURNING ONTO THE RWY THE EXAMINER SUDDENLY ORDERED ME TO SWING THE ACFT AROUND TO THE L. AT THIS MOMENT I ALSO COULD SEE A MULTI-ENG PLANE IN THE FINAL PHASE OF THE APCH. I GAVE FULL THROTTLE ON THE R ENG AND CLRED THE RWY. THE APCHING ACFT MADE A GAR. I STILL DO NOT UNDERSTAND WHY NOBODY IN MY ACFT COULD SEE THE APCHING ACFT. THIS POSSIBLE DANGEROUS SIT COULD HAVE BEEN AVOIDED BY GIVING POS RPTS VIA UNICOM BY THE APCHING ACFT AS WELL AS MORE CAREFUL SCANNING OF THE APCH PATH BY MYSELF.