LEAR25 FLT CREW HAS A RWY INCURSION AT SAF DUE TO MISINTERP OF AMENDED DEP CLRNC.

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DEPARTING SANTA FE; NM; ON AN FAR 135 IFR CHARTER. A DEP CLRNC WAS RECEIVED AND THE TAXI CHKLIST WAS BEING COMPLETED AS THE ACFT WAS NEARING RWY 2 AT SAF. A NEW DEP WAS RECEIVED JUST PRIOR TO THE HOLD LINE. 'AFTER TKOF; TURN L DIRECT ON COURSE AND CLB TO FL(?). THE COPLT READ BACK THE CLRNC AS I; THE CAPT; STARTED THE ROLL ONTO THE RWY FOR TKOF. THE CREW MISTAKENLY UNDERSTOOD THE CLRNC AS A 'TKOF' CLRNC AND PULLED ONTO THE RWY. THE TWR INSTANTLY CLRED THE CREW FOR A TKOF AND THERE WAS NO FURTHER MENTION OF THE CLRNC. THE TWR TOLD US TO CONTACT DEP AND THERE WAS NO FURTHER MENTION OF THE INCIDENT. PROB: THE CREW HAD PLANNED ON A STANDARD DEP AND A LAST MIN CHANGE AT THE END OF THE TXWY WITH THE VERBIAGE THAT USUALLY IS ASSOCIATED WITH A TKOF CLRNC SEEMED TO CAUSE BOTH PLTS TO MISS THE ACTUAL CLRNC AND DID NOT VERIFY OR HEAR THE ACTUAL WORDS 'CLRED FOR TKOF.' ONE HEARS WHAT YOU EXPECT TO HEAR AND NOT WHAT IS REALLY SAID. PREVENTION OF RECURRENCE: #1 IS TO JUST SLOW DOWN! LISTEN AND VERIFY THE CLRNC. IT IS OK TO READ BACK A CLRNC; BUT IT MUST BE UNDERSTOOD. WHEN A CLRNC IS GIVEN; IT SHOULD NOT BE GIVEN IN SUCH A WAY THAT IT CAN BE MISUNDERSTOOD AS WELL. IN THIS CASE THE DEP HEADING AND ALT WAS GIVEN FIRST BEFORE THE TKOF CLRNC; WHICH WAS OK; BUT JUST NOT STANDARD. WE; AS A CREW; HAVE GONE OVER THIS PROB AND MADE SOME ADJUSTMENTS TO OUR PROCS. WE HAVE ADDED A NEW CHK. WE BOTH HAVE TO VERIFY WE HEARD THE WORDS 'CLRED FOR TKOF' BEFORE WE ENTER THE ACTIVE RWY.