RWY INCURSION; UNAUTH RWY ENTRY.

Narrative

AFTER LNDG ON RWY 5R; MMMX; WAS CLRED BY TWR TO EXIT ON TXWY E AND HOLD SHORT OF RWY 5L. ACFT WAS SLOWED BY CAPT AND TURNED L ONTO TXWY E. AFTER CLRING RWY; FO CONTACTED OPS ON #2 VHF; AND ASKED THE OPS AGENT TO STATE THE GATE NUMBER WHICH THE AGENT HAD BEEN UNABLE TO STATE ON INITIAL RADIO CONTACT ABOUT 20 MINS BEFORE LNDG. OPS AGENT REPLY TO THE GATE INFO REQUEST WAS; YOU ARE CLRED TO GATE. THE SPEAKERS AND AUDIO MIXER SWITCHES WERE SET IN THE COCKPIT IN SUCH A WAY THAT CAPT HEARD THE AGENT'S XMISSION AT ABOUT THE SAME VOLUME LEVEL AS THE #1 VHF WHICH WAS BEING USED FOR ATC COMS. BELIEVING THAT IT WAS A CTLR WHO SAID; YOU ARE CLRED TO GATE; CAPT ALLOWED THE ACFT TO CONTINUE TO ROLL AT TAXI SPD TOWARD THE INTXN OF TXWY E AND RWY 5L. HE THEN LOOKED DOWN THE RWY FOR CONFLICTING TFC; SAW AN ACR X MD-80 TRAVELLING SLOWLY ENOUGH TO TURN SAFELY AT E2 TXWY AND LET THE ACFT CONTINUE TO ROLL SLOWLY ONTO THE EDGE OF RWY 5L. AS IT BECAME APPARENT THAT THE MD-80 WAS NOT GOING TO USE TXWY E2 TO CAPT AND AS IT BECAME APPARENT THAT 757 WOULD NOT BE STOPPED SHORT OF RWY 5L; BOTH FO AND THE TWR CTLR TOLD CAPT TO STOP AT ABOUT THE SAME TIME HE WAS APPLYING THE BRAKES TO STOP THE ACFT WHICH HE DID WITH ABOUT 2 FT OF THE NOSE OVER THE E EDGE OF THE RWY. THE MD-80 ON ROLLOUT ON RWY 5L DID NOT TURN OFF AT TXWY E2; BUT CONTINUED AT TAXI SPD TO TXWY B; ITS R WING TIP CLRING THE NOSE OF THE 757 BY ABOUT 30-40 FT AT A SAFE RATE OF SPD.